X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/31d22c319b73be63a4919405e465781fbccc72f7..37b849dca4dfd855212a763662825e:/doc/doc-docbook/spec.xfpt diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 6e8cf206e..5a757c4ed 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -1,3 +1,4 @@ + . ///////////////////////////////////////////////////////////////////////////// . This is the primary source of the Exim Manual. It is an xfpt document that is . converted into DocBook XML for subsequent conversion into printable and online @@ -45,7 +46,7 @@ . Update the Copyright year (only) when changing content. . ///////////////////////////////////////////////////////////////////////////// -.set previousversion "4.96" +.set previousversion "4.97" .include ./local_params .set ACL "access control lists (ACLs)" @@ -54,7 +55,7 @@ .set drivernamemax "64" .macro copyyear -2022 +2023 .endmacro . ///////////////////////////////////////////////////////////////////////////// @@ -76,6 +77,16 @@ . --- table with four columns. For cases when the option name is given with . --- a space, so that it can be split, a fifth argument is used for the . --- index entry. +. --- Also one for multiple option def headings be grouped in a single +. --- table (but without the split capability). + +.macro otable +.itable all 0 0 4 8* left 6* center 6* center 6* right +.endmacro + +.macro orow +.row "&%$1%&" "Use: &'$2'&" "Type: &'$3'&" "Default: &'$4'&" +.endmacro .macro option .arg 5 @@ -84,8 +95,19 @@ .arg -5 .oindex "&%$1%&" .endarg -.itable all 0 0 4 8* left 6* center 6* center 6* right -.row "&%$1%&" "Use: &'$2'&" "Type: &'$3'&" "Default: &'$4'&" +.otable +.orow "$1" "$2" "$3" "$4" +.endtable +.endmacro + +.macro options +.eacharg +.oindex "&%$+1%&" +.endeach 4 +.otable +.eacharg +.orow "$+1" "$+2" "$+3" "$+4" +.endeach 4 .endtable .endmacro @@ -443,10 +465,11 @@ Please do not ask for configuration help in the bug-tracker. The following Exim mailing lists exist: .table2 140pt -.row &'exim-announce@exim.org'& "Moderated, low volume announcements list" -.row &'exim-users@exim.org'& "General discussion list" -.row &'exim-dev@exim.org'& "Discussion of bugs, enhancements, etc." -.row &'exim-cvs@exim.org'& "Automated commit messages from the VCS" +.row &'exim-announce@lists.exim.org'& "Moderated, low volume announcements list" +.row &'exim-users@lists.exim.org'& "General discussion list" +.row &'exim-users-de@lists.exim.org'& "General discussion list in German language" +.row &'exim-dev@lists.exim.org'& "Discussion of bugs, enhancements, etc." +.row &'exim-cvs@lists.exim.org'& "Automated commit messages from the VCS" .endtable You can subscribe to these lists, change your existing subscriptions, and view @@ -948,9 +971,10 @@ User filters are run as part of the routing process, described below. .cindex "base36" .cindex "Darwin" .cindex "Cygwin" -Every message handled by Exim is given a &'message id'& which is sixteen +.cindex "exim_msgdate" +Every message handled by Exim is given a &'message id'& which is 23 characters long. It is divided into three parts, separated by hyphens, for -example &`16VDhn-0001bo-D3`&. Each part is a sequence of letters and digits, +example &`16VDhn-000000001bo-D342`&. Each part is a sequence of letters and digits, normally encoding numbers in base 62. However, in the Darwin operating system (Mac OS X) and when Exim is compiled to run under Cygwin, base 36 (avoiding the use of lower case letters) is used instead, because the message @@ -971,20 +995,24 @@ started to be received, to a granularity of one second. That is, this field contains the number of seconds since the start of the epoch (the normal Unix way of representing the date and time of day). .next -After the first hyphen, the next six characters are the id of the process that -received the message. +After the first hyphen, the next +eleven +characters are the id of the process that received the message. .next -There are two different possibilities for the final two characters: +There are two different possibilities for the final four characters: .olist .oindex "&%localhost_number%&" If &%localhost_number%& is not set, this value is the fractional part of the -time of reception, normally in units of 1/2000 of a second, but for systems +time of reception, normally in units of +microseconds. +but for systems that must use base 36 instead of base 62 (because of case-insensitive file -systems), the units are 1/1000 of a second. +systems), the units are +2 us. .next -If &%localhost_number%& is set, it is multiplied by 200 (100) and added to -the fractional part of the time, which in this case is in units of 1/200 -(1/100) of a second. +If &%localhost_number%& is set, it is multiplied by +500000 (250000) and added to +the fractional part of the time, which in this case is in units of 2 us (4 us). .endlist .endlist @@ -994,6 +1022,10 @@ received by the same process, or by another process with the same (re-used) pid, it is guaranteed that the time will be different. In most cases, the clock will already have ticked while the message was being received. +The exim_msgdate utility (see section &<>&) can be +used to display the date, and optionally the process id, of an Exim +Message ID. + .section "Receiving mail" "SECID13" .cindex "receiving mail" @@ -2810,6 +2842,12 @@ of Exim is installed. It is not necessary to do this when other files that are referenced from the configuration (for example, alias files) are changed, because these are reread each time they are used. +Either a SIGTERM or a SIGINT signal should be used to cause the daemon +to cleanly shut down. +Subprocesses handling recceiving or delivering messages, +or for scanning the queue, +will not be affected by the termination of the daemon process. + .cmdopt -bdf This option has the same effect as &%-bd%& except that it never disconnects from the controlling terminal, even when no debugging is specified. @@ -2846,11 +2884,9 @@ defined and macros will be expanded. Because macros in the config file are often used for secrets, those are only available to admin users. -.new The word &"set"& at the start of a line, followed by a single space, is recognised specially as defining a value for a variable. The syntax is otherwise the same as the ACL modifier &"set ="&. -.wen .cmdopt -bem <&'filename'&> .cindex "testing" "string expansion" @@ -3258,6 +3294,12 @@ to the standard output. It is restricted to admin users, unless &%queue_list_requires_admin%& is set false. +.cmdopt -bpi +.cindex queue "list of message IDs" +This option operates like &%-bp%&, but only outputs message ids +(one per line). + + .cmdopt -bpr This option operates like &%-bp%&, but the output is not sorted into chronological order of message arrival. This can speed it up when there are @@ -3267,6 +3309,9 @@ going to be post-processed in a way that doesn't need the sorting. .cmdopt -bpra This option is a combination of &%-bpr%& and &%-bpa%&. +.cmdopt -bpri +This option is a combination of &%-bpr%& and &%-bpi%&. + .cmdopt -bpru This option is a combination of &%-bpr%& and &%-bpu%&. @@ -3967,7 +4012,7 @@ user. This option requests Exim to give up trying to deliver the listed messages, including any that are frozen. However, if any of the messages are active, their status is not altered. For non-bounce messages, a delivery error message -is sent to the sender, containing the text &"cancelled by administrator"&. +is sent to the sender. Bounce messages are just discarded. This option can be used only by an admin user. @@ -4397,13 +4442,17 @@ It is only relevant when the &%-bd%& (start listening daemon) option is also given. Normally the daemon creates this socket, unless a &%-oX%& and &*no*& &%-oP%& option is also present. -If this option is given then the socket will not be created. This could be -required if the system is running multiple daemons. +If this option is given then the socket will not be created. This is required +if the system is running multiple daemons, in which case it should +be used on all. +The features supported by the socket will not be available in such cases. The socket is currently used for .ilist fast ramp-up of queue runner processes .next +caching compiled regexes +.next obtaining a current queue size .endlist @@ -4489,22 +4538,30 @@ every domain. Addresses are routed, local deliveries happen, but no remote transports are run. Performance will be best if the &%queue_run_in_order%& option is false. -If that is so and the &%queue_fast_ramp%& option is true then -in the first phase of the run, +If that is so and +the &%queue_fast_ramp%& option is true +and a daemon-notifier socket is available +then in the first phase of the run, once a threshold number of messages are routed for a given host, a delivery process is forked in parallel with the rest of the scan. .cindex "hints database" "remembering routing" The hints database that remembers which messages are waiting for specific hosts -is updated, as if delivery to those hosts had been deferred. After this is -complete, a second, normal queue scan happens, with routing and delivery taking -place as normal. Messages that are routed to the same host should mostly be +is updated, as if delivery to those hosts had been deferred. + +After the first queue scan complete, +a second, normal queue scan is done, with routing and delivery taking +place as normal. +Messages that are routed to the same host should mostly be delivered down a single SMTP .cindex "SMTP" "passed connection" .cindex "SMTP" "multiple deliveries" .cindex "multiple SMTP deliveries" connection because of the hints that were set up during the first queue scan. -This option may be useful for hosts that are connected to the Internet + +Two-phase queue runs should be used on systems which, even intermittently, +have a large queue (such as mailing-list operators). +They may also be useful for hosts that are connected to the Internet intermittently. .vitem &%-q[q]i...%& @@ -4591,6 +4648,13 @@ combined daemon at system boot time is to use a command such as Such a daemon listens for incoming SMTP calls, and also starts a queue runner process every 30 minutes. +.cindex "named queues" "queue runners" +It is possible to set up runners for multiple named queues within one daemon, +For example: +.code +exim -qGhipri/2m -q10m -qqGmailinglist/1h +.endd + When a daemon is started by &%-q%& with a time value, but without &%-bd%&, no pid file is written unless one is explicitly requested by the &%-oP%& option. @@ -5103,6 +5167,10 @@ The following classes of macros are defined: &` _DRIVER_ROUTER_* `& router drivers &` _DRIVER_TRANSPORT_* `& transport drivers &` _DRIVER_AUTHENTICATOR_* `& authenticator drivers +&` _EXP_COND_* `& expansion conditions +&` _EXP_ITEM_* `& expansion items +&` _EXP_OP_* `& expansion operators +&` _EXP_VAR_* `& expansion variables &` _LOG_* `& log_selector values &` _OPT_MAIN_* `& main config options &` _OPT_ROUTERS_* `& generic router options @@ -6559,15 +6627,17 @@ cause parts of the string to be replaced by data that is obtained from the lookup. Lookups of this type are conditional expansion items. Different results can be defined for the cases of lookup success and failure. See chapter &<>&, where string expansions are described in detail. -The key for the lookup is &*specified*& as part of the string expansion. +The key for the lookup is &*specified*& as part of the string to be expanded. .next Lists of domains, hosts, and email addresses can contain lookup requests as a way of avoiding excessively long linear lists. In this case, the data that is returned by the lookup is often (but not always) discarded; whether the lookup succeeds or fails is what really counts. These kinds of list are described in chapter &<>&. -The key for the lookup is &*implicit*&, -given by the context in which the list is expanded. +Depending on the lookup type (see below) +the key for the lookup may need to be &*specified*& as above +or may be &*implicit*&, +given by the context in which the list is being checked. .endlist String expansions, lists, and lookups interact with each other in such a way @@ -6586,6 +6656,7 @@ Be careful to distinguish between the following two examples: domains = ${lookup{$sender_host_address}lsearch{/some/file}} domains = lsearch;/some/file .endd +.ilist The first uses a string expansion, the result of which must be a domain list. The key for an expansion-style lookup must be given explicitly. No strings have been specified for a successful or a failing lookup; the @@ -6599,9 +6670,10 @@ file that is searched could contain lines like this: When the lookup succeeds, the result of the expansion is a list of domains (and possibly other types of item that are allowed in domain lists). .cindex "tainted data" "de-tainting" -.cindex "de-tainting" "using a lookup expansion"" +.cindex "de-tainting" "using a lookup expansion" The result of the expansion is not tainted. +.next In the second example, the lookup is a single item in a domain list. It causes Exim to use a lookup to see if the domain that is being processed can be found in the file. @@ -6615,7 +6687,8 @@ matches the list item. The key for a list-style lookup is implicit, from the lookup context, if the lookup is a single-key type (see below). -For query-style lookup types the key must be given explicitly. +For query-style lookup types the query must be given explicitly. +.endlist It is possible, though no doubt confusing, to use both kinds of lookup at once. Consider a file containing lines like this: @@ -6660,11 +6733,18 @@ If this is given and the lookup (either underlying implementation or cached value) returns data, the result is replaced with a non-tainted version of the lookup key. + .next .cindex "query-style lookup" "definition of" The &'query-style'& type accepts a generalized database query. No particular key value is assumed by Exim for query-style lookups. You can use whichever Exim variables you need to construct the database query. + +For the string-expansion kind of lookups, the query is given in the first +bracketed argument of the &${lookup ...}$& expansion. +For the list-argument kind of lookup the quury is given by the remainder of the +list item after the first semicolon. + .cindex "tainted data" "quoting for lookups" If tainted data is used in the query then it should be quuted by using the &*${quote_*&<&'lookup-type'&>&*:*&<&'string'&>&*}*& expansion operator @@ -6690,11 +6770,11 @@ libraries and header files before building Exim. .cindex "single-key lookup" "list of types" The following single-key lookup types are implemented: -.ilist +.subsection cdb .cindex "cdb" "description of" .cindex "lookup" "cdb" .cindex "binary zero" "in lookup key" -&(cdb)&: The given file is searched as a Constant DataBase file, using the key +The given file is searched as a Constant DataBase file, using the key string without a terminating binary zero. The cdb format is designed for indexed files that are read frequently and never updated, except by total re-creation. As such, it is particularly suitable for large files containing @@ -6710,11 +6790,12 @@ A cdb distribution is not needed in order to build Exim with cdb support, because the code for reading cdb files is included directly in Exim itself. However, no means of building or testing cdb files is provided with Exim, so you need to obtain a cdb distribution in order to do this. -.next + +.subsection dbm .cindex "DBM" "lookup type" .cindex "lookup" "dbm" .cindex "binary zero" "in lookup key" -&(dbm)&: Calls to DBM library functions are used to extract data from the given +Calls to DBM library functions are used to extract data from the given DBM file by looking up the record with the given key. A terminating binary zero is included in the key that is passed to the DBM library. See section &<>& for a discussion of DBM libraries. @@ -6726,25 +6807,27 @@ using Berkeley DB versions 3 or 4, it opens existing databases for reading with the DB_UNKNOWN option. This enables it to handle any of the types of database that the library supports, and can be useful for accessing DBM files created by other applications. (For earlier DB versions, DB_HASH is always used.) -.next + +.subsection dbmjz .cindex "lookup" "dbmjz" .cindex "lookup" "dbm &-- embedded NULs" .cindex "sasldb2" .cindex "dbmjz lookup type" -&(dbmjz)&: This is the same as &(dbm)&, except that the lookup key is +This is the same as &(dbm)&, except that the lookup key is interpreted as an Exim list; the elements of the list are joined together with ASCII NUL characters to form the lookup key. An example usage would be to authenticate incoming SMTP calls using the passwords from Cyrus SASL's &_/etc/sasldb2_& file with the &(gsasl)& authenticator or Exim's own &(cram_md5)& authenticator. -.next + +.subsection dbmnz .cindex "lookup" "dbmnz" .cindex "lookup" "dbm &-- terminating zero" .cindex "binary zero" "in lookup key" .cindex "Courier" .cindex "&_/etc/userdbshadow.dat_&" .cindex "dbmnz lookup type" -&(dbmnz)&: This is the same as &(dbm)&, except that a terminating binary zero +This is the same as &(dbm)&, except that a terminating binary zero is not included in the key that is passed to the DBM library. You may need this if you want to look up data in files that are created by or shared with some other application that does not use terminating zeros. For example, you need to @@ -6752,15 +6835,13 @@ use &(dbmnz)& rather than &(dbm)& if you want to authenticate incoming SMTP calls using the passwords from Courier's &_/etc/userdbshadow.dat_& file. Exim's utility program for creating DBM files (&'exim_dbmbuild'&) includes the zeros by default, but has an option to omit them (see section &<>&). -.next + +.subsection dsearch .cindex "lookup" "dsearch" .cindex "dsearch lookup type" -&(dsearch)&: The given file must be an -absolute -directory path; this is searched for an entry +The given file must be an absolute directory path; this is searched for an entry whose name is the key by calling the &[lstat()]& function. -The key may not -contain any forward slash characters. +The key may not contain any forward slash characters. If &[lstat()]& succeeds then so does the lookup. .cindex "tainted data" "dsearch result" The result is regarded as untainted. @@ -6789,10 +6870,11 @@ and symlinks. An example of how this lookup can be used to support virtual domains is given in section &<>&. -.next + +.subsection iplsearch .cindex "lookup" "iplsearch" .cindex "iplsearch lookup type" -&(iplsearch)&: The given file is a text file containing keys and data. A key is +The given file is a text file containing keys and data. A key is terminated by a colon or white space or the end of the line. The keys in the file must be IP addresses, or IP addresses with CIDR masks. Keys that involve IPv6 addresses must be enclosed in quotes to prevent the first internal colon @@ -6825,11 +6907,11 @@ One option is supported, "ret=full", to request the return of the entire line rather than omitting the key portion. Note however that the key portion will have been de-quoted. -.next +.subsection json .cindex lookup json .cindex json "lookup type" .cindex JSON expansions -&(json)&: The given file is a text file with a JSON structure. +The given file is a text file with a JSON structure. An element of the structure is extracted, defined by the search key. The key is a list of subelement selectors (colon-separated by default but changeable in the usual way) @@ -6844,11 +6926,11 @@ is returned. For elements of type string, the returned value is de-quoted. -.next +.subsection lmdb .cindex LMDB .cindex lookup lmdb .cindex database lmdb -&(lmdb)&: The given file is an LMDB database. +The given file is an LMDB database. LMDB is a memory-mapped key-value store, with API modeled loosely on that of BerkeleyDB. See &url(https://symas.com/products/lightning-memory-mapped-database/) @@ -6863,12 +6945,12 @@ You will need to separately create the LMDB database file, possibly using the &"mdb_load"& utility. -.next +.subsection lsearch .cindex "linear search" .cindex "lookup" "lsearch" .cindex "lsearch lookup type" .cindex "case sensitivity" "in lsearch lookup" -&(lsearch)&: The given file is a text file that is searched linearly for a +The given file is a text file that is searched linearly for a line beginning with the search key, terminated by a colon or white space or the end of the line. The search is case-insensitive; that is, upper and lower case letters are treated as the same. The first occurrence of the key that is found @@ -6898,17 +6980,17 @@ contents (see section &<>&). An optional colon is permitted after quoted keys (exactly as for unquoted keys). There is no special handling of quotes for the data part of an &(lsearch)& line. -.next +.subsection nis .cindex "NIS lookup type" .cindex "lookup" "NIS" .cindex "binary zero" "in lookup key" -&(nis)&: The given file is the name of a NIS map, and a NIS lookup is done with +The given file is the name of a NIS map, and a NIS lookup is done with the given key, without a terminating binary zero. There is a variant called &(nis0)& which does include the terminating binary zero in the key. This is reportedly needed for Sun-style alias files. Exim does not recognize NIS aliases; the full map names must be used. -.next +.subsection (n)wildlsearch .cindex "wildlsearch lookup type" .cindex "lookup" "wildlsearch" .cindex "nwildlsearch lookup type" @@ -6924,32 +7006,29 @@ Like &(lsearch)&, the testing is done case-insensitively. However, keys in the file that are regular expressions can be made case-sensitive by the use of &`(-i)`& within the pattern. The following forms of wildcard are recognized: -. ==== As this is a nested list, any displays it contains must be indented -. ==== as otherwise they are too far to the left. - .olist The string may begin with an asterisk to mean &"ends with"&. For example: .code - *.a.b.c data for anything.a.b.c - *fish data for anythingfish +*.a.b.c data for anything.a.b.c +*fish data for anythingfish .endd .next The string may begin with a circumflex to indicate a regular expression. For example, for &(wildlsearch)&: .code - ^\N\d+\.a\.b\N data for .a.b +^\N\d+\.a\.b\N data for .a.b .endd Note the use of &`\N`& to disable expansion of the contents of the regular expression. If you are using &(nwildlsearch)&, where the keys are not string-expanded, the equivalent entry is: .code - ^\d+\.a\.b data for .a.b +^\d+\.a\.b data for .a.b .endd The case-insensitive flag is set at the start of compiling the regular expression, but it can be turned off by using &`(-i)`& at an appropriate point. For example, to make the entire pattern case-sensitive: .code - ^(?-i)\d+\.a\.b data for .a.b +^(?-i)\d+\.a\.b data for .a.b .endd If the regular expression contains white space or colon characters, you must @@ -6970,7 +7049,7 @@ is used to implement &((n)wildlsearch)& means that the string may begin with a lookup name terminated by a semicolon, and followed by lookup data. For example: .code - cdb;/some/file data for keys that match the file +cdb;/some/file data for keys that match the file .endd The data that is obtained from the nested lookup is discarded. .endlist olist @@ -6983,13 +7062,12 @@ be followed by optional colons. &((n)wildlsearch)& can &'not'& be turned into a DBM or cdb file, because those lookup types support only literal keys. -.next +.subsection spf .cindex "spf lookup type" .cindex "lookup" "spf" -&(spf)&: If Exim is built with SPF support, manual lookups can be done +If Exim is built with SPF support, manual lookups can be done (as opposed to the standard ACL condition method). For details see section &<>&. -.endlist ilist .section "Query-style lookup types" "SECTquerystylelookups" @@ -6998,44 +7076,50 @@ For details see section &<>&. The supported query-style lookup types are listed below. Further details about many of them are given in later sections. -.ilist +.subsection dnsdb .cindex "DNS" "as a lookup type" .cindex "lookup" "DNS" -&(dnsdb)&: This does a DNS search for one or more records whose domain names +This does a DNS search for one or more records whose domain names are given in the supplied query. The resulting data is the contents of the records. See section &<>&. -.next + +.subsection ibase .cindex "InterBase lookup type" .cindex "lookup" "InterBase" -&(ibase)&: This does a lookup in an InterBase database. -.next +This does a lookup in an InterBase database. + +.subsection ldap .cindex "LDAP" "lookup type" .cindex "lookup" "LDAP" -&(ldap)&: This does an LDAP lookup using a query in the form of a URL, and +This does an LDAP lookup using a query in the form of a URL, and returns attributes from a single entry. There is a variant called &(ldapm)& that permits values from multiple entries to be returned. A third variant called &(ldapdn)& returns the Distinguished Name of a single entry instead of any attribute values. See section &<>&. -.next + +.subsection mysql .cindex "MySQL" "lookup type" .cindex "lookup" "MySQL" -&(mysql)&: The format of the query is an SQL statement that is passed to a +The format of the query is an SQL statement that is passed to a MySQL database. See section &<>&. -.next + +.subsection nisplus .cindex "NIS+ lookup type" .cindex "lookup" "NIS+" -&(nisplus)&: This does a NIS+ lookup using a query that can specify the name of +This does a NIS+ lookup using a query that can specify the name of the field to be returned. See section &<>&. -.next + +.subsection oracle .cindex "Oracle" "lookup type" .cindex "lookup" "Oracle" -&(oracle)&: The format of the query is an SQL statement that is passed to an +The format of the query is an SQL statement that is passed to an Oracle database. See section &<>&. -.next + +.subsection passwd .cindex "lookup" "passwd" .cindex "passwd lookup type" .cindex "&_/etc/passwd_&" -&(passwd)& is a query-style lookup with queries that are just user names. The +This is a query-style lookup with queries that are just user names. The lookup calls &[getpwnam()]& to interrogate the system password data, and on success, the result string is the same as you would get from an &(lsearch)& lookup on a traditional &_/etc/passwd file_&, though with &`*`& for the @@ -7043,32 +7127,33 @@ password value. For example: .code *:42:42:King Rat:/home/kr:/bin/bash .endd -.next + +.subsection pgsql .cindex "PostgreSQL lookup type" .cindex "lookup" "PostgreSQL" -&(pgsql)&: The format of the query is an SQL statement that is passed to a +The format of the query is an SQL statement that is passed to a PostgreSQL database. See section &<>&. -.next +.subsection redis .cindex "Redis lookup type" .cindex lookup Redis -&(redis)&: The format of the query is either a simple get or simple set, +The format of the query is either a simple get or simple set, passed to a Redis database. See section &<>&. -.next +.subsection sqlite .cindex "sqlite lookup type" .cindex "lookup" "sqlite" -&(sqlite)&: The format of the query is +The format of the query is an SQL statement that is passed to an SQLite database. See section &<>&. -.next -&(testdb)&: This is a lookup type that is used for testing Exim. It is +.subsection testdb +This is a lookup type that is used for testing Exim. It is not likely to be useful in normal operation. -.next + +.subsection whoson .cindex "whoson lookup type" .cindex "lookup" "whoson" -. --- still http:-only, 2018-09-07 -&(whoson)&: &'Whoson'& (&url(http://whoson.sourceforge.net)) is a protocol that +&'Whoson'& (&url(http://whoson.sourceforge.net)) is a protocol that allows a server to check whether a particular (dynamically allocated) IP address is currently allocated to a known (trusted) user and, optionally, to obtain the identity of the said user. For SMTP servers, &'Whoson'& was popular @@ -7083,7 +7168,6 @@ The query consists of a single IP address. The value returned is the name of the authenticated user, which is stored in the variable &$value$&. However, in this example, the data in &$value$& is not used; the result of the lookup is one of the fixed strings &"yes"& or &"no"&. -.endlist @@ -7251,6 +7335,11 @@ dot-separated components; a key such as &`*fict.example`& in a database file is useless, because the asterisk in a partial matching subject key is always followed by a dot. +When the lookup is done from a string-expansion, +the variables &$1$& and &$2$& contain the wild and non-wild parts of the key +during the expansion of the replacement text. +They return to their previous values at the end of the lookup item. + @@ -7301,10 +7390,13 @@ of the following form is provided: .code ${quote_:} .endd -For example, the safest way to write the NIS+ query is +For example, the way to write the NIS+ query is .code [name="${quote_nisplus:$local_part}"] .endd +.cindex "tainted data" "in lookups" +&*All*& tainted data used in a query-style lookup must be quoted +using a mechanism appropriate for the lookup type. See chapter &<>& for full coverage of string expansions. The quote operator can be used for all lookup types, but has no effect for single-key lookups, since no quoting is ever needed in their key strings. @@ -7789,7 +7881,8 @@ connection timeout (the system timeout is used), no user or password, no limit on the number of entries returned, and no time limit on queries. When a DN is quoted in the USER= setting for LDAP authentication, Exim -removes any URL quoting that it may contain before passing it LDAP. Apparently +removes any URL quoting that it may contain before passing it to the LDAP library. +Apparently some libraries do this for themselves, but some do not. Removing the URL quoting has two advantages: @@ -8125,7 +8218,7 @@ daemon as in the other SQL databases. .oindex &%sqlite_dbfile%& There are two ways of specifying the file. -The first is is by using the &%sqlite_dbfile%& main option. +The first is by using the &%sqlite_dbfile%& main option. The second, which allows separate files for each query, is to use an option appended, comma-separated, to the &"sqlite"& lookup type word. The option is the word &"file"&, then an equals, @@ -9513,7 +9606,6 @@ value. Nevertheless the &%-be%& option can be useful for checking out file and database lookups, and the use of expansion operators such as &%sg%&, &%substr%& and &%nhash%&. -.new When reading lines from the standard input, macros can be defined and ACL variables can be set. For example: @@ -9522,7 +9614,6 @@ MY_MACRO = foo set acl_m_myvar = bar .endd Such macros and variables can then be used in later input lines. -.wen Exim gives up its root privilege when it is called with the &%-be%& option, and instead runs under the uid and gid it was called with, to prevent users from @@ -9638,7 +9729,8 @@ Example use (as an ACL modifier): .code add_header = :at_start:${authresults {$primary_hostname}} .endd -This is safe even if no authentication results are available. +This is safe even if no authentication results are available +and would generally be placed in the DATA ACL. .vitem "&*${certextract{*&<&'field'&>&*}{*&<&'certificate'&>&*}&&& @@ -9896,8 +9988,10 @@ leading and trailing quotes are removed from the returned value. After expansion, <&'string'&> is interpreted as a list, colon-separated by default, but the separator can be changed in the usual way (&<>&). For each item -in this list, its value is place in &$item$&, and then the condition is -evaluated. If the condition is true, &$item$& is added to the output as an +in this list, its value is placed in &$item$&, and then the condition is +evaluated. +Any modification of &$value$& by this evaluation is discarded. +If the condition is true, &$item$& is added to the output as an item in a new list; if the condition is false, the item is discarded. The separator used for the output list is the same as the one used for the input, but a separator setting is not included in the output. For example: @@ -9905,7 +9999,8 @@ input, but a separator setting is not included in the output. For example: ${filter{a:b:c}{!eq{$item}{b}}} .endd yields &`a:c`&. At the end of the expansion, the value of &$item$& is restored -to what it was before. See also the &%map%& and &%reduce%& expansion items. +to what it was before. +See also the &%map%& and &%reduce%& expansion items. .vitem &*${hash{*&<&'string1'&>&*}{*&<&'string2'&>&*}{*&<&'string3'&>&*}}*& @@ -10424,6 +10519,11 @@ Defines whether or not a write-shutdown is done on the connection after sending the request. Values are &"yes"& (the default) or &"no"& (preferred, eg. by some webservers). +.next +&*sni*& +Controls the use of Server Name Identification on the connection. +Any nonempty value will be the SNI sent; TLS will be forced. + .next &*tls*& Controls the use of TLS on the connection. @@ -10496,20 +10596,32 @@ At the end of a &*reduce*& expansion, the values of &$item$& and &$value$& are restored to what they were before. See also the &%filter%& and &%map%& expansion items. +. A bit of a special-case logic error in writing an expansion; +. probably not worth including in the mainline of documentation. +. If only we had footnotes (the html output variant is the problem). +. +. .new +. &*Note*&: if an &'expansion condition'& is used in <&'string3'&> +. and that condition modifies &$value$&, +. then the string expansions dependent on the condition cannot use +. the &$value$& of the reduce iteration. +. .wen + .vitem &*$rheader_*&<&'header&~name'&>&*:*&&~or&~&*$rh_*&<&'header&~name'&>&*:*& This item inserts &"raw"& header lines. It is described with the &%header%& expansion item in section &<>& above. -.vitem "&*${run <&'options'&> {*&<&'command&~arg&~list'&>&*}{*&<&'string1'&>&*}&&& +.vitem "&*${run<&'options'&> {*&<&'command&~string'&>&*}{*&<&'string1'&>&*}&&& {*&<&'string2'&>&*}}*&" .cindex "expansion" "running a command" .cindex "&%run%& expansion item" This item runs an external command, as a subprocess. -One option is supported after the word &'run'&, comma-separated. +One option is supported after the word &'run'&, comma-separated +and without whitespace. If the option &'preexpand'& is not used, -the command string is split into individual arguments by spaces -and then each argument is expanded. +the command string before expansion is split into individual arguments by spaces +and then each argument is separately expanded. Then the command is run in a separate process, but under the same uid and gid. As in other command executions from Exim, a shell is not used by default. If the command requires @@ -10521,9 +10633,9 @@ potential attacker; a careful assessment for security vulnerabilities should be done. If the option &'preexpand'& is used, -the command and its arguments are first expanded as one string. The result is -split apart into individual arguments by spaces, and then the command is run -as above. +the command string is first expanded as a whole. +The expansion result is split apart into individual arguments by spaces, +and then the command is run as above. Since the arguments are split by spaces, when there is a variable expansion which has an empty result, it will cause the situation that the argument will simply be omitted when the program is actually executed by Exim. If the @@ -10565,6 +10677,7 @@ shell must be invoked directly, such as with: .code ${run{/bin/bash -c "/usr/bin/id >/tmp/id"}{yes}{yes}} .endd +Note that &$value$& will not persist beyond the reception of a single message. .vindex "&$runrc$&" The return code from the command is put in the variable &$runrc$&, and this @@ -10987,6 +11100,22 @@ abbreviation &%h%& can be used when &%hash%& is used as an operator. +.vitem &*${headerwrap_*&<&'cols'&>&*_*&<&'limit'&>&*:*&<&'string'&>&*}*& +.cindex header "wrapping operator" +.cindex expansion "header wrapping" +This operator line-wraps its argument in a way useful for headers. +The &'cols'& value gives the column number to wrap after, +the &'limit'& gives a limit number of result characters to truncate at. +Either just the &'limit'& and the preceding underbar, or both, can be omitted; +the defaults are 80 and 998. +Wrapping will be inserted at a space if possible before the +column number is reached. +Whitespace at a chosen wrap point is removed. +A line-wrap consists of a newline followed by a tab, +and the tab is counted as 8 columns. + + + .vitem &*${hex2b64:*&<&'hexstring'&>&*}*& .cindex "base64 encoding" "conversion from hex" .cindex "expansion" "hex to base64" @@ -11648,6 +11777,7 @@ Consider using a dsearch lookup. .cindex "first delivery" .cindex "expansion" "first delivery test" .cindex "&%first_delivery%& expansion condition" +.cindex retry condition This condition, which has no data, is true during a message's first delivery attempt. It is false during any subsequent delivery attempts. @@ -11675,10 +11805,11 @@ all items in the list, the overall condition is true. .endlist Note that negation of &*forany*& means that the condition must be false for all items for the overall condition to succeed, and negation of &*forall*& means -that the condition must be false for at least one item. In this example, the -list separator is changed to a comma: +that the condition must be false for at least one item. + +Example: .code -${if forany{<, $recipients}{match{$item}{^user3@}}{yes}{no}} +${if forany{$recipients_list}{match{$item}{^user3@}}{yes}{no}} .endd The value of &$item$& is saved and restored while &%forany%& or &%forall%& is being processed, to enable these expansion items to be nested. @@ -11732,8 +11863,8 @@ Case and collation order are defined per the system C locale. SRS decode. See SECT &<>& for details. -.vitem &*inlist&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& &&& - &*inlisti&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& +.vitem &*inlist&~{*&<&'subject'&>&*}{*&<&'list'&>&*}*& &&& + &*inlisti&~{*&<&'subject'&>&*}{*&<&'list'&>&*}*& .cindex "string" "comparison" .cindex "list" "iterative conditions" Both strings are expanded; the second string is treated as a list of simple @@ -11933,6 +12064,10 @@ Exim was built with the EXPAND_LISTMATCH_RHS option. Consult section &<>& for further details of these patterns. +The variable &$value$& will be set for a successful match and can be +used in the success clause of an &%if%& expansion item using the condition. +Any previous &$value$& is restored after the if. + .vitem &*match_local_part&~{*&<&'string1'&>&*}{*&<&'string2'&>&*}*& .cindex "domain list" "in expansion condition" .cindex "address list" "in expansion condition" @@ -13277,10 +13412,18 @@ The main use of this variable is expected to be to distinguish between rejections of MAIL and rejections of RCPT. .tvar &$recipients$& -This variable contains a list of envelope recipients for a message. A comma and -a space separate the addresses in the replacement text. However, the variable -is not generally available, to prevent exposure of Bcc recipients in -unprivileged users' filter files. You can use &$recipients$& only in these +.tvar &$recipients_list$& +These variables both contain the envelope recipients for a message. + +The first uses a comma and a space separate the addresses in the replacement text. +&*Note*&: an address can legitimately contain a comma; +this variable is not intended for further processing. + +The second is a proper Exim list; colon-separated. + +However, the variables +are not generally available, to prevent exposure of Bcc recipients in +unprivileged users' filter files. You can use either of them only in these cases: .olist @@ -13344,7 +13487,8 @@ This is an obsolete name for &$bounce_return_size_limit$&. .cindex "router" "name" .cindex "name" "of router" .vindex "&$router_name$&" -During the running of a router this variable contains its name. +During the running of a router, or a transport called, +this variable contains the router name. .vitem &$runrc$& .cindex "return code" "from &%run%& expansion" @@ -13635,6 +13779,11 @@ there actually are, because many other connections may come and go while a single connection is being processed. When a child process terminates, the daemon decrements its copy of the variable. +.vitem &$smtp_notquit_reason$& +.vindex "&$smtp_notquit_reason$&" +When the not-QUIT ACL is running, this variable is set to a string +that indicates the reason for the termination of the SMTP connection. + .vitem "&$sn0$& &-- &$sn9$&" These variables are copies of the values of the &$n0$& &-- &$n9$& accumulators that were current at the end of the system filter file. This allows a system @@ -15311,11 +15460,8 @@ $primary_hostname-$tod_epoch-testing See section &<>& for details of how this value is used. -.option check_log_inodes main integer 100 -See &%check_spool_space%& below. - - -.option check_log_space main integer 10M +.options check_log_inodes main integer 100 &&& + check_log_space main integer 10M See &%check_spool_space%& below. .oindex "&%check_rfc2047_length%&" @@ -15330,11 +15476,8 @@ of the RFC, generates overlong encoded words. If &%check_rfc2047_length%& is set false, Exim recognizes encoded words of any length. -.option check_spool_inodes main integer 100 -See &%check_spool_space%& below. - - -.option check_spool_space main integer 10M +.options check_spool_inodes main integer 100 &&& + check_spool_space main integer 10M .cindex "checking disk space" .cindex "disk space, checking" .cindex "spool directory" "checking space" @@ -15413,17 +15556,15 @@ This option specifies one or more default SMTP ports on which the Exim daemon listens. See chapter &<>& for details of how it is used. For backward compatibility, &%daemon_smtp_port%& (singular) is a synonym. -.option daemon_startup_retries main integer 9 +.options daemon_startup_retries main integer 9 &&& + daemon_startup_sleep main time 30s .cindex "daemon startup, retrying" -This option, along with &%daemon_startup_sleep%&, controls the retrying done by +These options control the retrying done by the daemon at startup when it cannot immediately bind a listening socket (typically because the socket is already in use): &%daemon_startup_retries%& defines the number of retries after the first failure, and &%daemon_startup_sleep%& defines the length of time to wait between retries. -.option daemon_startup_sleep main time 30s -See &%daemon_startup_retries%&. - .option delay_warning main "time list" 24h .cindex "warning of delay" .cindex "delay warning, specifying" @@ -15586,7 +15727,10 @@ by a setting such as this: .code dns_again_means_nonexist = *.in-addr.arpa .endd -This option applies to all DNS lookups that Exim does. It also applies when the +This option applies to all DNS lookups that Exim does, +except for TLSA lookups (where knowing about such failures +is security-relevant). +It also applies when the &[gethostbyname()]& or &[getipnodebyname()]& functions give temporary errors, since these are most likely to be caused by DNS lookup problems. The &(dnslookup)& router has some options of its own for controlling what happens @@ -15926,6 +16070,7 @@ search the file multiple times for non-existent users, and also cause delay. .option freeze_tell main "string list, comma separated" unset .cindex "freezing messages" "sending a message when freezing" +.cindex "frozen messages" "sending a message when freezing" On encountering certain errors, or when configured to do so in a system filter, ACL, or special router, Exim freezes a message. This means that no further delivery attempts take place until an administrator thaws the message, or the @@ -15941,7 +16086,8 @@ log. If you configure freezing in a filter or ACL, you must arrange for any logging that you require. -.option gecos_name main string&!! unset +.options gecos_name main string&!! unset &&& + gecos_pattern main string unset .cindex "HP-UX" .cindex "&""gecos""& field, parsing" Some operating systems, notably HP-UX, use the &"gecos"& field in the system @@ -15966,9 +16112,6 @@ gecos_pattern = ([^,]*) gecos_name = $1 .endd -.option gecos_pattern main string unset -See &%gecos_name%& above. - .option gnutls_compat_mode main boolean unset This option controls whether GnuTLS is used in compatibility mode in an Exim @@ -16166,6 +16309,9 @@ This option is obsolete, and retained only for backward compatibility, because nowadays the ACL specified by &%acl_smtp_connect%& can also reject incoming connections immediately. +If the connection is on a TLS-on-connect port then the TCP connection is +just dropped. Otherwise, an SMTP error is sent first. + The ability to give an immediate rejection (either by this option or using an ACL) is provided for use in unusual cases. Many hosts will just try again, sometimes without much delay. Normally, it is better to use an ACL to reject @@ -16185,10 +16331,8 @@ local processes, you must create a host list with an empty item. For example: .code hosts_connection_nolog = : .endd -.new The hosts affected by this option also do not log "no MAIL in SMTP connection" lines, as may commonly be produced by a monitoring system. -.wen .option hosts_require_alpn main "host list&!!" unset @@ -16267,7 +16411,8 @@ dealing with other kinds of frozen message, see &%auto_thaw%& and &%timeout_frozen_after%&. -.option ignore_fromline_hosts main "host list&!!" unset +.options ignore_fromline_hosts main "host list&!!" unset &&& + ignore_fromline_local main boolean false .cindex "&""From""& line" .cindex "UUCP" "&""From""& line" Some broken SMTP clients insist on sending a UUCP-like &"From&~"& line before @@ -16279,8 +16424,6 @@ process rather than a remote host, and is using &%-bs%& to inject the messages, &%ignore_fromline_local%& must be set to achieve this effect. -.option ignore_fromline_local main boolean false -See &%ignore_fromline_hosts%& above. .option keep_environment main "string list" unset .cindex "environment" "values from" @@ -16435,7 +16578,8 @@ has more details about &'Sender:'& processing. -.option local_from_prefix main string unset +.options local_from_prefix main string unset &&& + local_from_suffix main string unset When Exim checks the &'From:'& header line of locally submitted messages for matching the login id (see &%local_from_check%& above), it can be configured to ignore certain prefixes and suffixes in the local part of the address. This is @@ -16455,10 +16599,6 @@ matches the actual sender address that is constructed from the login name and qualify domain. -.option local_from_suffix main string unset -See &%local_from_prefix%& above. - - .option local_interfaces main "string list" "see below" This option controls which network interfaces are used by the daemon for listening; they are also used to identify the local host when routing. Chapter @@ -16864,7 +17004,6 @@ to be used in conjunction with &(oracle)& lookups (see section &<>&). The option is available only if Exim has been built with Oracle support. -.new .option panic_coredump main boolean false This option is rarely needed but can help for some debugging investigations. If set, when an internal error is detected by Exim which is sufficient @@ -16875,7 +17014,6 @@ then a coredump is requested. Note that most systems require additional administrative configuration to permit write a core file for a setuid program, which is Exim's common installed configuration. -.wen .option percent_hack_domains main "domain list&!!" unset .cindex "&""percent hack""&" @@ -16898,16 +17036,11 @@ a good idea to reject recipient addresses with percent characters in their local parts. Exim's default configuration does this. -.option perl_at_start main boolean false -.cindex "Perl" -This option is available only when Exim is built with an embedded Perl -interpreter. See chapter &<>& for details of its use. - - -.option perl_startup main string unset +.options perl_at_start main boolean false &&& + perl_startup main string unset .cindex "Perl" -This option is available only when Exim is built with an embedded Perl -interpreter. See chapter &<>& for details of its use. +These options are available only when Exim is built with an embedded Perl +interpreter. See chapter &<>& for details of their use. .option perl_taintmode main boolean false .cindex "Perl" @@ -17119,7 +17252,7 @@ and &%-odi%& command line options override &%queue_only%& unless &%queue_only_load%&, and &%smtp_accept_queue%&. -.option queue_only_file main string unset +.option queue_only_file main "string list" unset .cindex "queueing incoming messages" .cindex "message" "queueing by file existence" This option can be set to a colon-separated list of absolute path names, each @@ -17656,13 +17789,16 @@ This facility is only available on Linux. .cindex "banner for SMTP" .cindex "welcome banner for SMTP" .cindex "customizing" "SMTP banner" -This string, which is expanded every time it is used, is output as the initial +If a connect ACL does not supply a message, +this string (which is expanded every time it is used) is output as the initial positive response to an SMTP connection. The default setting is: .code smtp_banner = $smtp_active_hostname ESMTP Exim \ $version_number $tod_full .endd -Failure to expand the string causes a panic error. If you want to create a +Failure to expand the string causes a panic error; +a forced fail just closes the connection. +If you want to create a multiline response to the initial SMTP connection, use &"\n"& in the string at appropriate points, but not at the end. Note that the 220 code is not included in this string. Exim adds it automatically (several times in the case of a @@ -17797,7 +17933,9 @@ non-SMTP command lines are sent first. -.option smtp_ratelimit_hosts main "host list&!!" unset +.options smtp_ratelimit_hosts main "host list&!!" unset &&& + smtp_ratelimit_mail main string unset &&& + smtp_ratelimit_rcpt main string unset .cindex "SMTP" "rate limiting" .cindex "limit" "rate of message arrival" .cindex "RCPT" "rate limiting" @@ -17840,13 +17978,6 @@ seconds, increasing by a factor of 1.05 each time. The second setting applies delays to RCPT commands when more than four occur in a single message. -.option smtp_ratelimit_mail main string unset -See &%smtp_ratelimit_hosts%& above. - - -.option smtp_ratelimit_rcpt main string unset -See &%smtp_ratelimit_hosts%& above. - .option smtp_receive_timeout main time&!! 5m .cindex "timeout" "for SMTP input" @@ -18247,7 +18378,7 @@ is not required the &%tls_advertise_hosts%& option should be set empty. .cindex ALPN "set acceptable names for server" If this option is set, the TLS library supports ALPN, -and the client offers either more than +and the client offers either more than one ALPN name or a name which does not match the list, the TLS connection is declined. @@ -18404,20 +18535,23 @@ prior to the 4.80 release, as Debian used to patch Exim to raise the minimum acceptable bound from 1024 to 2048. -.option tls_eccurve main string&!! &`auto`& +.option tls_eccurve main string list&!! &`auto`& .cindex TLS "EC cryptography" -This option selects a EC curve for use by Exim when used with OpenSSL. -It has no effect when Exim is used with GnuTLS. +This option selects EC curves for use by Exim when used with OpenSSL. +It has no effect when Exim is used with GnuTLS +(the equivalent can be done using a priority string for the +&%tls_require_ciphers%& option). -After expansion it must contain a valid EC curve parameter, such as -&`prime256v1`&, &`secp384r1`&, or &`P-512`&. Consult your OpenSSL manual -for valid selections. +After expansion it must contain +one or (only for OpenSSL versiona 1.1.1 onwards) more +EC curve names, such as &`prime256v1`&, &`secp384r1`&, or &`P-521`&. +Consult your OpenSSL manual for valid curve names. For OpenSSL versions before (and not including) 1.0.2, the string &`auto`& selects &`prime256v1`&. For more recent OpenSSL versions &`auto`& tells the library to choose. -If the option expands to an empty string, no EC curves will be enabled. +If the option expands to an empty string, the effect is undefined. .option tls_ocsp_file main string&!! unset @@ -19011,12 +19145,25 @@ This applies to all of the SRV, MX, AAAA, A lookup sequence. .cindex "router" "restricting to specific domains" .vindex "&$domain_data$&" If this option is set, the router is skipped unless the current domain matches -the list. If the match is achieved by means of a file lookup, the data that the -lookup returned for the domain is placed in &$domain_data$& for use in string +the list. +The data returned by the list check +is placed in &$domain_data$& for use in string expansions of the driver's private options and in the transport. See section &<>& for a list of the order in which preconditions are evaluated. +A complex example, using a file like: +.code +alice@dom1 +bill@dom1 +maggie@dom1 +.endd +and checking both domain and local_part +.code +domains = ${domain:${lookup {$local_part@$domain} lseach,ret=key {/path/to/accountsfile}}} +local_parts = ${local_part:${lookup {$local_part@$domain} lseach,ret=key {/path/to/accountsfile}}} +.endd + .option driver routers string unset @@ -19380,7 +19527,7 @@ example: local_parts = dbm;/usr/local/specials/$domain_data .endd .vindex "&$local_part_data$&" -If the match is achieved by a lookup, the data that the lookup returned +the data returned by the list check for the local part is placed in the variable &$local_part_data$& for use in expansions of the router's private options or in the transport. You might use this option, for @@ -22352,7 +22499,7 @@ its removal from incoming messages, so that delivered messages can safely be resent to other recipients. &*Note:*& If used on a transport handling multiple recipients -(the smtp transport unless &%rcpt_max%& is 1, the appendfile, pipe or lmtp +(the smtp transport unless &%max_rcpt%& is 1, the appendfile, pipe or lmtp transport if &%batch_max%& is greater than 1) then information about Bcc recipients will be leaked. Doing so is generally not advised. @@ -22645,8 +22792,11 @@ If unset, or expanding to an empty string, no filtering is done. When the message is about to be written out, the command specified by &%transport_filter%& is started up in a separate, parallel process, and the entire message, including the header lines, is passed to it on its standard -input (this in fact is done from a third process, to avoid deadlock). The -command must be specified as an absolute path. +input (this in fact is done from a third process, to avoid deadlock). +The command must be specified as an absolute path. + +The process run by the command must use its standard input as the message +data to be transformed, and write the results on its standard output. The lines of the message that are written to the transport filter are terminated by newline (&"\n"&). The message is passed to the filter before any @@ -22716,7 +22866,17 @@ example: transport_filter = '/bin/cmd${if eq{$host}{a.b.c}{1}{2}}' .endd This runs the command &(/bin/cmd1)& if the host name is &'a.b.c'&, and -&(/bin/cmd2)& otherwise. If double quotes had been used, they would have been +&(/bin/cmd2)& otherwise. + +Option strings in general have any fully-surrounding double quote wrapping +removed early in parsing (see &<>&). +Then, for this option, quotes protect against whitespace being +regarded as a separator while splitting into the command argument vector. +Either double or single quotes can be used here; +the former interprets backlash-quoted charachters +and the latter does not. + +If double quotes had been used in this example, they would have been stripped by Exim when it read the option's value. When the value is used, if the single quotes were missing, the line would be split into two items, &`/bin/cmd${if`& and &`eq{$host}{a.b.c}{1}{2}`&, and an error would occur when @@ -25580,12 +25740,16 @@ hard failure if required. See also &%hosts_try_auth%&, and chapter &<>& for details of authentication. -.option hosts_request_ocsp smtp "host list&!!" * +.option hosts_request_ocsp smtp "host list&!!" "see below" .cindex "TLS" "requiring for certain servers" Exim will request a Certificate Status on a TLS session for any host that matches this list. &%tls_verify_certificates%& should also be set for the transport. +The default is &"**"& if DANE is not in use for the connection, +or if DANE-TA us used. +It is empty if DANE-EE is used. + .option hosts_require_alpn smtp "host list&!!" unset .cindex ALPN "require negotiation in client" .cindex TLS ALPN @@ -25727,12 +25891,18 @@ If this option is set true when the &%protocol%& option is set to &"lmtp"&, the string &`IGNOREQUOTA`& is added to RCPT commands, provided that the LMTP server has advertised support for IGNOREQUOTA in its response to the LHLO command. -.option max_rcpt smtp integer 100 +.option max_rcpt smtp integer&!! 100 .cindex "RCPT" "maximum number of outgoing" -This option limits the number of RCPT commands that are sent in a single -SMTP message transaction. Each set of addresses is treated independently, and +This option, +after expansion, +limits the number of RCPT commands that are sent in a single +SMTP message transaction. +A value setting of zero disables the limit. + +If a constant is given, +each set of addresses is treated independently, and so can cause parallel connections to the same host if &%remote_max_parallel%& -permits this. A value setting of zero disables the limit. +permits this. .option message_linelength_limit smtp integer 998 @@ -26005,7 +26175,8 @@ This option give a list of hosts for which, while verifying the server certificate, checks will be included on the host name (note that this will generally be the result of a DNS MX lookup) -versus Subject and Subject-Alternate-Name fields. Wildcard names are permitted +versus the Subject-Alternate-Name (or, if none, Subject-Name) fields. +Wildcard names are permitted, limited to being the initial component of a 3-or-more component FQDN. There is no equivalent checking on client certificates. @@ -26055,7 +26226,7 @@ If both this option and &%tls_try_verify_hosts%& are unset operation is as if this option selected all hosts. &*Warning*&: Including a host in &%tls_verify_hosts%& does not require that connections use TLS. -Fallback to in-clear communication will be done unless restricted by +Fallback to in-clear communication will be done unless restricted by the &%hosts_require_tls%& option. .option utf8_downconvert smtp integer&!! -1 @@ -27539,7 +27710,6 @@ no successful authentication. Successful authentication sets up information used by the &%authresults%& expansion item. -.new .cindex authentication "failure event, server" If an authenticator is run and does not succeed, an event (see &<>&) of type "auth:fail" is raised. @@ -27550,7 +27720,6 @@ will be valid. If the event is serviced and a string is returned then the string will be logged instead of the default log line. See <> for details on events. -.wen .section "Testing server authentication" "SECID169" @@ -27629,7 +27798,6 @@ Exim abandons trying to send the message to the host for the moment. It will try again later. If there are any backup hosts available, they are tried in the usual way. -.new .next .cindex authentication "failure event, client" If the response to authentication is a permanent error (5&'xx'& code), @@ -27639,7 +27807,6 @@ While the event is being processed the variable will be valid. If the event is serviced and a string is returned then the string will be logged. See <> for details on events. -.wen .next If the response to authentication is a permanent error (5&'xx'& code), Exim @@ -28196,7 +28363,7 @@ Dovecot 2 POP/IMAP server, which can support a number of authentication methods. Note that Dovecot must be configured to use auth-client not auth-userdb. If you are using Dovecot to authenticate POP/IMAP clients, it might be helpful to use the same mechanisms for SMTP authentication. This is a server -authenticator only. There is only one option: +authenticator only. There is only one non-generic option: .option server_socket dovecot string unset @@ -28208,6 +28375,7 @@ authenticators for different mechanisms. For example: dovecot_plain: driver = dovecot public_name = PLAIN + server_advertise_condition = ${if def:tls_in_cipher} server_socket = /var/run/dovecot/auth-client server_set_id = $auth1 @@ -28217,6 +28385,11 @@ dovecot_ntlm: server_socket = /var/run/dovecot/auth-client server_set_id = $auth1 .endd + +&*Note*&: plaintext authentication methods such as PLAIN and LOGIN +should not be advertised on cleartext SMTP connections. +See the discussion in section &<>&. + If the SMTP connection is encrypted, or if &$sender_host_address$& is equal to &$received_ip_address$& (that is, the connection is local), the &"secured"& option is passed in the Dovecot authentication command. If, for a TLS @@ -28815,9 +28988,10 @@ for which it must have been requested via the (see &<>&). If an authenticator of this type is configured it is -run before any SMTP-level communication is done, +run immediately after a TLS connection being negotiated +(due to either STARTTLS or TLS-on-connect) and can authenticate the connection. -If it does, SMTP authentication is not offered. +If it does, SMTP authentication is not subsequently offered. A maximum of one authenticator of this type may be present. @@ -29023,8 +29197,8 @@ When using OpenSSL, this option is ignored. (If an API is found to let OpenSSL be configured in this way, let the Exim Maintainers know and we'll likely use it). .next -With GnuTLS, if an explicit list is used for the &%tls_privatekey%& main option -main option, it must be ordered to match the &%tls_certificate%& list. +With GnuTLS, if an explicit list is used for the &%tls_privatekey%& main option, +it must be ordered to match the &%tls_certificate%& list. .next Some other recently added features may only be available in one or the other. This should be documented with the feature. If the documentation does not @@ -29375,7 +29549,7 @@ For outgoing SMTP deliveries, &$tls_out_cipher$& is used and logged (again depending on the &%tls_cipher%& log selector). -.subsection "Requesting and verifying client certificates" SECID183 +.subsection "Requesting and verifying client certificates" .cindex "certificate" "verification of client" .cindex "TLS" "client certificate verification" If you want an Exim server to request a certificate when negotiating a TLS @@ -29428,86 +29602,7 @@ Because it is often a long text string, it is not included in the log line or certificate is supplied, &$tls_in_peerdn$& is empty. -.section "Revoked certificates" "SECID184" -.cindex "TLS" "revoked certificates" -.cindex "revocation list" -.cindex "certificate" "revocation list" -.cindex "OCSP" "stapling" -Certificate issuing authorities issue Certificate Revocation Lists (CRLs) when -certificates are revoked. If you have such a list, you can pass it to an Exim -server using the global option called &%tls_crl%& and to an Exim client using -an identically named option for the &(smtp)& transport. In each case, the value -of the option is expanded and must then be the name of a file that contains a -CRL in PEM format. -The downside is that clients have to periodically re-download a potentially huge -file from every certificate authority they know of. - -The way with most moving parts at query time is Online Certificate -Status Protocol (OCSP), where the client verifies the certificate -against an OCSP server run by the CA. This lets the CA track all -usage of the certs. It requires running software with access to the -private key of the CA, to sign the responses to the OCSP queries. OCSP -is based on HTTP and can be proxied accordingly. - -The only widespread OCSP server implementation (known to this writer) -comes as part of OpenSSL and aborts on an invalid request, such as -connecting to the port and then disconnecting. This requires -re-entering the passphrase each time some random client does this. - -The third way is OCSP Stapling; in this, the server using a certificate -issued by the CA periodically requests an OCSP proof of validity from -the OCSP server, then serves it up inline as part of the TLS -negotiation. This approach adds no extra round trips, does not let the -CA track users, scales well with number of certs issued by the CA and is -resilient to temporary OCSP server failures, as long as the server -starts retrying to fetch an OCSP proof some time before its current -proof expires. The downside is that it requires server support. - -Unless Exim is built with the support disabled, -or with GnuTLS earlier than version 3.3.16 / 3.4.8 -support for OCSP stapling is included. - -There is a global option called &%tls_ocsp_file%&. -The file specified therein is expected to be in DER format, and contain -an OCSP proof. Exim will serve it as part of the TLS handshake. This -option will be re-expanded for SNI, if the &%tls_certificate%& option -contains &`tls_in_sni`&, as per other TLS options. - -Exim does not at this time implement any support for fetching a new OCSP -proof. The burden is on the administrator to handle this, outside of -Exim. The file specified should be replaced atomically, so that the -contents are always valid. Exim will expand the &%tls_ocsp_file%& option -on each connection, so a new file will be handled transparently on the -next connection. - -When built with OpenSSL Exim will check for a valid next update timestamp -in the OCSP proof; if not present, or if the proof has expired, it will be -ignored. - -For the client to be able to verify the stapled OCSP the server must -also supply, in its stapled information, any intermediate -certificates for the chain leading to the OCSP proof from the signer -of the server certificate. There may be zero or one such. These -intermediate certificates should be added to the server OCSP stapling -file named by &%tls_ocsp_file%&. - -Note that the proof only covers the terminal server certificate, -not any of the chain from CA to it. - -There is no current way to staple a proof for a client certificate. - -.code - A helper script "ocsp_fetch.pl" for fetching a proof from a CA - OCSP server is supplied. The server URL may be included in the - server certificate, if the CA is helpful. - - One failure mode seen was the OCSP Signer cert expiring before the end - of validity of the OCSP proof. The checking done by Exim/OpenSSL - noted this as invalid overall, but the re-fetch script did not. -.endd - - -.section "Caching of static server configuration items" "SECTserverTLScache" +.subsection "Caching of static server configuration items" "SSECTserverTLScache" .cindex certificate caching .cindex privatekey caching .cindex crl caching @@ -29553,10 +29648,10 @@ A HUP signal is sufficient for this. The value &"system"& results in no caching under GnuTLS. The macro _HAVE_TLS_CA_CACHE will be defined if the suffix for "system" -is acceptable in configurations for the Exim executavble. +is acceptable in configurations for the Exim executable. Caching of the system Certificate Authorities bundle can -save siginificant time and processing on every TLS connection +save significant time and processing on every TLS connection accepted by Exim. @@ -29726,10 +29821,10 @@ A HUP signal is sufficient for this. The value &"system"& results in no caching under GnuTLS. The macro _HAVE_TLS_CA_CACHE will be defined if the suffix for "system" -is acceptable in configurations for the Exim executavble. +is acceptable in configurations for the Exim executable. Caching of the system Certificate Authorities bundle can -save siginificant time and processing on every TLS connection +save significant time and processing on every TLS connection initiated by Exim. @@ -29813,6 +29908,7 @@ When Exim is built against GnuTLS, SNI support is available as of GnuTLS 0.5.10. (Its presence predates the current API which Exim uses, so if Exim built, then you have SNI support). +.subsection ALPN .cindex TLS ALPN .cindex ALPN "general information" .cindex TLS "Application Layer Protocol Names" @@ -29823,7 +29919,7 @@ connection. The client for the connection proposes a set of protocol names, and the server responds with a selected one. It is not, as of 2021, commonly used for SMTP connections. -However, to guard against misirected or malicious use of web clients +However, to guard against misdirected or malicious use of web clients (which often do use ALPN) against MTA ports, Exim by default check that there is no incompatible ALPN specified by a client for a TLS connection. If there is, the connection is rejected. @@ -29833,7 +29929,7 @@ The behaviour of both client and server can be configured using the options &%tls_alpn%& and &%hosts_require_alpn%&. There are no variables providing observability. Some feature-specific logging may appear on denied connections, but this -depends on the behavious of the peer +depends on the behaviour of the peer (not all peers can send a feature-specific TLS Alert). This feature is available when Exim is built with @@ -29982,6 +30078,94 @@ For information on creating self-signed CA certificates and using them to sign user certificates, see the &'General implementation overview'& chapter of the Open-source PKI book, available online at &url(https://sourceforge.net/projects/ospkibook/). + + +.subsection "Revoked certificates" +.cindex "TLS" "revoked certificates" +.cindex "revocation list" +.cindex "certificate" "revocation list" +.cindex "OCSP" "stapling" +There are three ways for a certificate to be made unusable +before its expiry. + +.ilist +Certificate issuing authorities issue Certificate Revocation Lists (CRLs) when +certificates are revoked. If you have such a list, you can pass it to an Exim +server using the global option called &%tls_crl%& and to an Exim client using +an identically named option for the &(smtp)& transport. In each case, the value +of the option is expanded and must then be the name of a file that contains a +CRL in PEM format. +The downside is that clients have to periodically re-download a potentially huge +file from every certificate authority they know of. + +.next +The way with most moving parts at query time is Online Certificate +Status Protocol (OCSP), where the client verifies the certificate +against an OCSP server run by the CA. This lets the CA track all +usage of the certs. It requires running software with access to the +private key of the CA, to sign the responses to the OCSP queries. OCSP +is based on HTTP and can be proxied accordingly. + +The only widespread OCSP server implementation (known to this writer) +comes as part of OpenSSL and aborts on an invalid request, such as +connecting to the port and then disconnecting. This requires +re-entering the passphrase each time some random client does this. + +.next +The third way is OCSP Stapling; in this, the server using a certificate +issued by the CA periodically requests an OCSP proof of validity from +the OCSP server, then serves it up inline as part of the TLS +negotiation. This approach adds no extra round trips, does not let the +CA track users, scales well with number of certs issued by the CA and is +resilient to temporary OCSP server failures, as long as the server +starts retrying to fetch an OCSP proof some time before its current +proof expires. The downside is that it requires server support. + +Unless Exim is built with the support disabled, +or with GnuTLS earlier than version 3.3.16 / 3.4.8 +support for OCSP stapling is included. + +There is a global option called &%tls_ocsp_file%&. +The file specified therein is expected to be in DER format, and contain +an OCSP proof. Exim will serve it as part of the TLS handshake. This +option will be re-expanded for SNI, if the &%tls_certificate%& option +contains &`tls_in_sni`&, as per other TLS options. + +Exim does not at this time implement any support for fetching a new OCSP +proof. The burden is on the administrator to handle this, outside of +Exim. The file specified should be replaced atomically, so that the +contents are always valid. Exim will expand the &%tls_ocsp_file%& option +on each connection, so a new file will be handled transparently on the +next connection. + +When built with OpenSSL Exim will check for a valid next update timestamp +in the OCSP proof; if not present, or if the proof has expired, it will be +ignored. + +For the client to be able to verify the stapled OCSP the server must +also supply, in its stapled information, any intermediate +certificates for the chain leading to the OCSP proof from the signer +of the server certificate. There may be zero or one such. These +intermediate certificates should be added to the server OCSP stapling +file named by &%tls_ocsp_file%&. + +Note that the proof only covers the terminal server certificate, +not any of the chain from CA to it. + +There is no current way to staple a proof for a client certificate. + +.code + A helper script "ocsp_fetch.pl" for fetching a proof from a CA + OCSP server is supplied. The server URL may be included in the + server certificate, if the CA is helpful. + + One failure mode seen was the OCSP Signer cert expiring before the end + of validity of the OCSP proof. The checking done by Exim/OpenSSL + noted this as invalid overall, but the re-fetch script did not. +.endd +.endlist + + .ecindex IIDencsmtp1 .ecindex IIDencsmtp2 @@ -30099,18 +30283,24 @@ DANE scales better than having to maintain (and communicate via side-channel) co for every possible target server. It also scales (slightly) better than having to maintain on an SMTP client a copy of the standard CAs bundle. It also means not having to pay a CA for certificates. -DANE requires a server operator to do three things: 1) run DNSSEC. This provides assurance to clients +DANE requires a server operator to do three things: +.olist +Run DNSSEC. This provides assurance to clients that DNS lookups they do for the server have not been tampered with. The domain MX record applying to this server, its A record, its TLSA record and any associated CNAME records must all be covered by DNSSEC. -2) add TLSA DNS records. These say what the server certificate for a TLS connection should be. -3) offer a server certificate, or certificate chain, in TLS connections which is is anchored by one of the TLSA records. +.next +Add TLSA DNS records. These say what the server certificate for a TLS connection should be. +.next +Offer a server certificate, or certificate chain, in TLS connections which is anchored by one of the TLSA records. +.endlist There are no changes to Exim specific to server-side operation of DANE. Support for client-side operation of DANE can be included at compile time by defining SUPPORT_DANE=yes in &_Local/Makefile_&. If it has been included, the macro "_HAVE_DANE" will be defined. +.subsection "DNS records" A TLSA record consist of 4 fields, the "Certificate Usage", the "Selector", the "Matching type", and the "Certificate Association Data". For a detailed description of the TLSA record see @@ -30191,6 +30381,7 @@ libraries. This means no MD5 and no SHA-1. SHA2-256 is the minimum for reliable interoperability (and probably the maximum too, in 2018). +.subsection "Interaction with OCSP" The use of OCSP-stapling should be considered, allowing for fast revocation of certificates (which would otherwise be limited by the DNS TTL on the TLSA records). However, this is likely to only be usable with DANE-TA. NOTE: the default of requesting OCSP for all hosts is modified iff DANE is in use, to: @@ -30211,6 +30402,7 @@ This modification of hosts_request_ocsp is only done if it has the default value those who use &%hosts_require_ocsp%&, should consider the interaction with DANE in their OCSP settings. +.subsection "Client configuration" For client-side DANE there are three new smtp transport options, &%hosts_try_dane%&, &%hosts_require_dane%& and &%dane_require_tls_ciphers%&. The &"require"& variant will result in failure if the target host is not @@ -30249,6 +30441,7 @@ verification evaluation is wanted, the above variables should be set appropriate The router and transport option &%dnssec_request_domains%& must not be set to &"never"&, and &%dnssec_require_domains%& is ignored. +.subsection Observability If verification was successful using DANE then the "CV" item in the delivery log line will show as "CV=dane". There is a new variable &$tls_out_dane$& which will have "yes" if @@ -30264,11 +30457,13 @@ required. This is intended to support TLS-reporting as defined in The &$event_data$& will be one of the Result Types defined in Section 4.3 of that document. +.subsection General Under GnuTLS, DANE is only supported from version 3.0.0 onwards. DANE is specified in published RFCs and decouples certificate authority trust selection from a "race to the bottom" of "you must trust everything for mail -to get through". There is an alternative technology called MTA-STS, which +to get through". +There is an alternative technology called MTA-STS, which instead publishes MX trust anchor information on an HTTPS website. At the time this text was last updated, MTA-STS was still a draft, not yet an RFC. Exim has no support for MTA-STS as a client, but Exim mail server operators @@ -30426,8 +30621,9 @@ accepted by an &%accept%& verb that has a &%message%& modifier, the contents of the message override the banner message that is otherwise specified by the &%smtp_banner%& option. -For tls-on-connect connections, the ACL is run after the TLS connection -is accepted (however, &%host_reject_connection%& is tested before). +For tls-on-connect connections, the ACL is run before the TLS connection +is accepted; if the ACL does not accept then the TCP connection is dropped without +any TLS startup attempt and without any SMTP response being transmitted. .subsection "The EHLO/HELO ACL" SECID192 @@ -31353,8 +31549,11 @@ the message modifier cannot override the 221 response code. The text in a &%message%& modifier is literal; any quotes are taken as literals, but because the string is expanded, backslash escapes are processed -anyway. If the message contains newlines, this gives rise to a multi-line SMTP +anyway. +If the message contains newlines, this gives rise to a multi-line SMTP response. +A long message line will also be split into multi-line SMTP responses, +on word boundaries if possible. .vindex "&$acl_verify_message$&" While the text is being expanded, the &$acl_verify_message$& variable @@ -31578,7 +31777,7 @@ pretrigger=<&'size'&> This option specifies a memory buffuer to be used immediate writes to file are done as normal. trigger=<&'reason'&> This option selects cause for the pretrigger buffer - see above) to be copied to file. A reason of $*now* + see above) to be copied to file. A reason of &*now*& take effect immediately; one of &*paniclog*& triggers on a write to the panic log. .endd @@ -31648,6 +31847,7 @@ work with. .vitem &*control&~=&~fakedefer/*&<&'message'&> .cindex "fake defer" .cindex "defer, fake" +.cindex fakedefer This control works in exactly the same way as &%fakereject%& (described below) except that it causes an SMTP 450 response after the message data instead of a 550 response. You must take care when using &%fakedefer%& because it causes the @@ -31657,6 +31857,7 @@ use &%fakedefer%& if the message is to be delivered normally. .vitem &*control&~=&~fakereject/*&<&'message'&> .cindex "fake rejection" .cindex "rejection, fake" +.cindex fakereject This control is permitted only for the MAIL, RCPT, and DATA ACLs, in other words, only when an SMTP message is being received. If Exim accepts the message, instead the final 250 response, a 550 rejection message is sent. @@ -31958,8 +32159,22 @@ Headers will not be removed from the message if the modifier is used in DATA, MIME or DKIM ACLs for a message delivered by cutthrough routing. More than one header can be removed at the same time by using a colon separated -list of header names. The header matching is case insensitive. Wildcards are -not permitted, nor is list expansion performed, so you cannot use hostlists to +list of header specifiers. +If a specifier does not start with a circumflex (^) +then it is treated as a header name. +The header name matching is case insensitive. +If it does, then it is treated as a (front-anchored) +regular expression applied to the whole header. + +&*Note*&: The colon terminating a header name will need to be doubled +if used in an RE, and there can legitimately be whitepace before it. + +Example: +.code +remove_header = \N^(?i)Authentication-Results\s*::\s*example.org;\N +.endd + +List expansion is not performed, so you cannot use hostlists to create a list of headers, however both connection and message variable expansion are performed (&%$acl_c_*%& and &%$acl_m_*%&), illustrated in this example: .code @@ -31968,14 +32183,14 @@ warn hosts = +internal_hosts warn message = Remove internal headers remove_header = $acl_c_ihdrs .endd -Header names for removal are accumulated during the MAIL, RCPT, and predata ACLs. +Header specifiers for removal are accumulated during the MAIL, RCPT, and predata ACLs. Matching header lines are removed from the message before processing the DATA and MIME ACLs. If multiple header lines match, all are removed. There is no harm in attempting to remove the same header twice nor in removing -a non-existent header. Further header lines to be removed may be accumulated -during the DATA and MIME ACLs, after which they are removed from the message, -if present. In the case of non-SMTP messages, headers to be removed are -accumulated during the non-SMTP ACLs, and are removed from the message after +a non-existent header. Further header specifiers for removal may be accumulated +during the DATA and MIME ACLs, after which matching headers are removed +if present. In the case of non-SMTP messages, remove specifiers are +accumulated during the non-SMTP ACLs, and are acted on after all the ACLs have run. If a message is rejected after DATA or by the non-SMTP ACL, there really is no effect because there is no logging of what headers would have been removed. @@ -32958,7 +33173,7 @@ address you should specify alternate list separators for both the outer The &%seen%& ACL condition can be used to test whether a situation has been previously met. It uses a hints database to record a timestamp against a key. -host. The syntax of the condition is: +The syntax of the condition is: .display &`seen =`& <&'optional flag'&><&'time interval'&> &`/`& <&'options'&> .endd @@ -33076,16 +33291,23 @@ the &%count=%& option. .subsection "Ratelimit options for what is being measured" ratoptmea .cindex "rate limiting" "per_* options" -The &%per_conn%& option limits the client's connection rate. It is not +.vlist +.vitem per_conn +.cindex "rate limiting" per_conn +This option limits the client's connection rate. It is not normally used in the &%acl_not_smtp%&, &%acl_not_smtp_mime%&, or &%acl_not_smtp_start%& ACLs. -The &%per_mail%& option limits the client's rate of sending messages. This is +.vitem per_mail +.cindex "rate limiting" per_conn +This option limits the client's rate of sending messages. This is the default if none of the &%per_*%& options is specified. It can be used in &%acl_smtp_mail%&, &%acl_smtp_rcpt%&, &%acl_smtp_predata%&, &%acl_smtp_mime%&, &%acl_smtp_data%&, or &%acl_not_smtp%&. -The &%per_byte%& option limits the sender's email bandwidth. It can be used in +.vitem per_byte +.cindex "rate limiting" per_conn +This option limits the sender's email bandwidth. It can be used in the same ACLs as the &%per_mail%& option, though it is best to use this option in the &%acl_smtp_mime%&, &%acl_smtp_data%& or &%acl_not_smtp%& ACLs; if it is used in an earlier ACL, Exim relies on the SIZE parameter given by the client @@ -33093,7 +33315,9 @@ in its MAIL command, which may be inaccurate or completely missing. You can follow the limit &'m'& in the configuration with K, M, or G to specify limits in kilobytes, megabytes, or gigabytes, respectively. -The &%per_rcpt%& option causes Exim to limit the rate at which recipients are +.vitem per_rcpt +.cindex "rate limiting" per_rcpt +This option causes Exim to limit the rate at which recipients are accepted. It can be used in the &%acl_smtp_rcpt%&, &%acl_smtp_predata%&, &%acl_smtp_mime%&, or &%acl_smtp_data%& ACLs. In &%acl_smtp_rcpt%& the rate is updated one recipient at a time; in the other @@ -33101,24 +33325,37 @@ ACLs the rate is updated with the total (accepted) recipient count in one go. No in either case the rate limiting engine will see a message with many recipients as a large high-speed burst. -The &%per_addr%& option is like the &%per_rcpt%& option, except it counts the +.vitem per_addr +.cindex "rate limiting" per_addr +This option is like the &%per_rcpt%& option, except it counts the number of different recipients that the client has sent messages to in the last time period. That is, if the client repeatedly sends messages to the same recipient, its measured rate is not increased. This option can only be used in &%acl_smtp_rcpt%&. -The &%per_cmd%& option causes Exim to recompute the rate every time the +.vitem per_cmd +.cindex "rate limiting" per_cmd +This option causes Exim to recompute the rate every time the condition is processed. This can be used to limit the rate of any SMTP command. If it is used in multiple ACLs it can limit the aggregate rate of multiple different commands. -The &%count=%& option can be used to alter how much Exim adds to the client's -measured rate. For example, the &%per_byte%& option is equivalent to -&`per_mail/count=$message_size`&. If there is no &%count=%& option, Exim +.vitem count +.cindex "rate limiting" count +This option can be used to alter how much Exim adds to the client's +measured rate. +A value is required, after an equals sign. +For example, the &%per_byte%& option is equivalent to +&`per_mail/count=$message_size`&. +If there is no &%count=%& option, Exim increases the measured rate by one (except for the &%per_rcpt%& option in ACLs -other than &%acl_smtp_rcpt%&). The count does not have to be an integer. +other than &%acl_smtp_rcpt%&). +The count does not have to be an integer. -The &%unique=%& option is described in section &<>& below. +.vitem unique +.cindex "rate limiting" unique +This option is described in section &<>& below. +.endlist .subsection "Ratelimit update modes" ratoptupd @@ -33658,7 +33895,7 @@ a specific address, and the other records information that applies to the entire domain (for example, that it accepts the local part &'postmaster'&). When an original callout fails, a detailed SMTP error message is given about -the failure. However, for subsequent failures use the cache data, this message +the failure. However, for subsequent failures that use the cache data, this message is not available. The expiry times for negative and positive address cache records are @@ -35805,6 +36042,7 @@ The system filter is run at the start of a delivery attempt, before any routing is done. If a message fails to be completely delivered at the first attempt, the system filter is run again at the start of every retry. If you want your filter to do something only once per message, you can make use +.cindex retry condition of the &%first_delivery%& condition in an &%if%& command in the filter to prevent it happening on retries. @@ -38696,6 +38934,7 @@ the following table: .display &`A `& authenticator name (and optional id and sender) &`C `& SMTP confirmation on delivery +&`Ci `& connection identifier &` `& command list for &"no mail in SMTP session"& &`CV `& certificate verification status &`D `& duration of &"no mail in SMTP session"& @@ -38784,7 +39023,7 @@ logging and the message has a DKIM signature header. .section "Reducing or increasing what is logged" "SECTlogselector" .cindex "log" "selectors" By setting the &%log_selector%& global option, you can disable some of Exim's -default logging, or you can request additional logging. The value of +default logging to the main log, or you can request additional logging. The value of &%log_selector%& is made up of names preceded by plus or minus characters. For example: .code @@ -38798,6 +39037,7 @@ selection marked by asterisks: .irow &`address_rewrite`&   "address rewriting" .irow &`all_parents`&   "all parents in => lines" .irow &`arguments`&   "command line arguments" +.irow &`connection_id`&   "connection identifier" .irow &`connection_reject`& * "connection rejections" .irow &`delay_delivery`& * "immediate delivery delayed" .irow &`deliver_time`&   "time taken to attempt delivery" @@ -38809,7 +39049,7 @@ selection marked by asterisks: .irow &`etrn`& * "ETRN commands" .irow &`host_lookup_failed`& * "as it says" .irow &`ident_timeout`&   "timeout for ident connection" -.irow &`incoming_interface`&   "local interface on <= and => lines" +.irow &`incoming_interface`&   "local interface & port on <= and => lines" .irow &`incoming_port`&   "remote port on <= lines" .irow &`lost_incoming_connection`& * "as it says (includes timeouts)" .irow &`millisec`&   "millisecond timestamps and RT,QT,DT,D times" @@ -38893,6 +39133,12 @@ because the arguments are checked before the configuration file is read. The only way to log such cases is to interpose a script such as &_util/logargs.sh_& between the caller and Exim. .next +.cindex "log" "connection identifier" +&%connection_identifier%&: An identifier for the accepted connection is added to +connection start and end lines and to message accept lines. +The identifier is tagged by Ci=. +The value is PID-based, so will reset on reboot and will wrap. +.next .cindex "log" "connection rejections" &%connection_reject%&: A log entry is written whenever an incoming SMTP connection is rejected, for whatever reason. @@ -39314,6 +39560,7 @@ the next chapter. The utilities described here are: .irow &<>& &'exim_tidydb'& "clean up a hints database" .irow &<>& &'exim_fixdb'& "patch a hints database" .irow &<>& &'exim_lock'& "lock a mailbox file" +.irow &<>& &'exim_msgdate'& "Message Ids for humans (exim_msgdate)" .endtable Another utility that might be of use to sites with many MTAs is Tom Kistner's @@ -39822,6 +40069,8 @@ Serializing delivery to a specific host (when &%serialize_hosts%& is set in an .next Limiting the concurrency of specific transports (when &%max_parallel%& is set in a transport) +.next +Recording EHLO-time facilities advertised by hosts .endlist @@ -40037,9 +40286,16 @@ exim_lock -q /var/spool/mail/spqr \ .endd Note that if a command is supplied, it must be entirely contained within the second argument &-- hence the quotes. -.ecindex IIDutils +.section "Message Ids for humans (exim_msgdate)" "SECTexim_msgdate" +.cindex "exim_msgdate" +The &'exim_msgdate'& utility is written by Andrew Aitchison and included in the Exim distribution. +This Perl script converts an Exim Mesage ID back into a human readable form. +For details of &'exim_msgdate'&'s options, run &'exim_msgdate'& with the &%--help%& option. + +Section &<>& (Message identification) describes Exim Mesage IDs. +.ecindex IIDutils . //////////////////////////////////////////////////////////////////////////// . //////////////////////////////////////////////////////////////////////////// @@ -41480,8 +41736,9 @@ RFC 6376 lists these tags as RECOMMENDED. Verification of DKIM signatures in SMTP incoming email is done for all messages for which an ACL control &%dkim_disable_verify%& has not been set. + .cindex DKIM "selecting signature algorithms" -Individual classes of signature algorithm can be ignored by changing +Individual classes of DKIM signature algorithm can be ignored by changing the main options &%dkim_verify_hashes%& or &%dkim_verify_keytypes%&. The &%dkim_verify_minimal%& option can be set to cease verification processing for a message once the first passing signature is found. @@ -41494,7 +41751,7 @@ For most purposes the default option settings suffice and the remainder of this section can be ignored. The results of verification are made available to the -&%acl_smtp_dkim%& ACL, which can examine and modify them. +&%acl_smtp_dkim%& ACL, which (for complex needs) can examine and modify them. A missing ACL definition defaults to accept. By default, the ACL is called once for each syntactically(!) correct signature in the incoming message. @@ -41559,6 +41816,12 @@ an identity. This is one of the list items from the expanded main option &%dkim_verify_signers%& (see above). .vitem &%$dkim_verify_status%& +So long as a DKIM ACL is defined +(it need do no more than accept, which is the default), +after all the DKIM ACL runs have completed, the value becomes a +colon-separated list of the values after each run. +The value is maintained for the MIME, PRDR and DATA ACLs. + Within the DKIM ACL, a string describing the general status of the signature. One of .ilist @@ -41587,11 +41850,6 @@ hash-method or key-size: set dkim_verify_reason = hash too weak or key too short .endd -So long as a DKIM ACL is defined (it need do no more than accept), -after all the DKIM ACL runs have completed, the value becomes a -colon-separated list of the values after each run. -This is maintained for the mime, prdr and data ACLs. - .vitem &%$dkim_verify_reason%& A string giving a little bit more detail when &%$dkim_verify_status%& is either "fail" or "invalid". One of @@ -41722,7 +41980,9 @@ In addition, two ACL conditions are provided: .vitem &%dkim_signers%& ACL condition that checks a colon-separated list of domains or identities for a match against the domain or identity that the ACL is currently verifying -(reflected by &%$dkim_cur_signer%&). This is typically used to restrict an ACL +(reflected by &%$dkim_cur_signer%&). +This condition is only usable in a DKIM ACL. +This is typically used to restrict an ACL verb to a group of domains or identities. For example: .code @@ -41738,7 +41998,18 @@ for that check for empty &$h_DKIM-Signature:$& in the data ACL. .vitem &%dkim_status%& ACL condition that checks a colon-separated list of possible DKIM verification -results against the actual result of verification. This is typically used +results against the actual result of verification, +given by &$dkim_verify_status$& if that is non-empty or "none" if empty. +.new +This condition may be used in DKIM, MIME, PRDR and DATA ACLs. +.wen + +A basic verification might be: +.code +deny !dkim_status = pass:none:invalid +.endd + +A more complex use could be to restrict an ACL verb to a list of verification outcomes, for example: .code @@ -41751,6 +42022,12 @@ deny sender_domains = paypal.com:paypal.de The possible status keywords are: 'none','invalid','fail' and 'pass'. Please see the documentation of the &%$dkim_verify_status%& expansion variable above for more information of what they mean. + +The condition is true if the status +.new +(or any of the list of status values) +.wen +is any one of the supplied list. .endlist @@ -41984,18 +42261,28 @@ encoding operation. If this value is empty the the expansion result will be empty. The third argument should be the recipient domain of the message when it arrived at this system. +All arguments are expanded before use. + +The result of the expansion is the replacement envelope-from (return path) +to be used. .endlist .cindex SRS decoding To decode an address use this expansion condition: .vlist .vitem &*inbound_srs&~{*&<&'local&~part'&>&*}{*&<&'secret'&>&*}*& -The first argument should be the recipient local prt as is was received. +The first argument should be the recipient local part as it was received. The second argument is the site secret. +Both arguments are expanded before use. If the messages is not for an SRS-encoded recipient the condition will -return false. If it is, the condition will return true and the variable +return false. +If it is, the condition will return true and the variable &$srs_recipient$& will be set to the decoded (original) value. + +If the second argument is empty then the condition returns true if +the first argument is in valid SRS formet, else false. +The variable &$srs_recipient$& is not set for this case. .endlist Example usage: @@ -42037,8 +42324,9 @@ Example usage: # one, plus the max_rcpt and return_path options remote_forwarded_smtp: driver = smtp - # modify the envelope from, for mails that we forward + # single-recipient so that $original_domain is valid max_rcpt = 1 + # modify the envelope from, for mails that we forward return_path = ${srs_encode {SRS_SECRET} {$return_path} {$original_domain}} .endd @@ -42145,7 +42433,7 @@ the DATA acl. .subsection ACL SSECDMARCACL .cindex DMARC "ACL condition" -DMARC checks cam be run on incoming SMTP messages by using the +DMARC checks can be run on incoming SMTP messages by using the &"dmarc_status"& ACL condition in the DATA ACL. You are required to call the &"spf"& condition first in the ACLs, then the &"dmarc_status"& condition. Putting this condition in the ACLs is required in order @@ -42693,8 +42981,8 @@ All other message types ignore the result string, and no other use is made of it. For a tcp:connect event, if the connection is being made to a proxy -then the address and port variables will be that of the proxy and not -the target system. +then the &$host_address$& and &$host_port$& variables +will be that of the proxy and not the target system. For tls:cert events, if GnuTLS is in use this will trigger only per chain element received on the connection.