-$Cambridge: exim/doc/doc-txt/NewStuff,v 1.81 2006/02/08 16:10:46 ph10 Exp $
+$Cambridge: exim/doc/doc-txt/NewStuff,v 1.145 2007/03/13 15:32:47 ph10 Exp $
New Features in Exim
--------------------
-This file contains descriptions of new features that have been added to Exim,
-but have not yet made it into the main manual (which is most conveniently
-updated when there is a relatively large batch of changes). The doc/ChangeLog
-file contains a listing of all changes, including bug fixes.
+This file contains descriptions of new features that have been added to Exim.
+Before a formal release, there may be quite a lot of detail so that people can
+test from the snapshots or the CVS before the documentation is updated. Once
+the documentation is updated, this file is reduced to a short list.
+
+Version 4.67
+------------
+
+ 1. There is a new log selector called smtp_no_mail, which is not included in
+ the default setting. When it is set, a line is written to the main log
+ whenever an accepted SMTP connection terminates without having issued a
+ MAIL command. This includes both the case when the connection is dropped,
+ and the case when QUIT is used. Note that it does not include cases where
+ the connection is rejected right at the start (by an ACL, or because there
+ are too many connections, or whatever). These cases already have their own
+ log lines.
+
+ The log line that is written contains the identity of the client in the
+ usual way, followed by D= and a time, which records the duration of the
+ connection. If the connection was authenticated, this fact is logged
+ exactly as it is for an incoming message, with an A= item. If the
+ connection was encrypted, CV=, DN=, and X= items may appear as they do for
+ an incoming message, controlled by the same logging options.
+
+ Finally, if any SMTP commands were issued during the connection, a C= item
+ is added to the line, listing the commands that were used. For example,
+
+ C=EHLO,QUIT
+
+ shows that the client issued QUIT straight after EHLO. If there were fewer
+ than 20 commands, they are all listed. If there were more than 20 commands,
+ the last 20 are listed, preceded by "...". However, with the default
+ setting of 10 for smtp_accep_max_nonmail, the connection will in any case
+ be aborted before 20 non-mail commands are processed.
+
+ 2. When an item in a dnslists list is followed by = and & and a list of IP
+ addresses, in order to restrict the match to specific results from the DNS
+ lookup, the behaviour was not clear when the lookup returned more than one
+ IP address. For example, consider the condition
+
+ dnslists = a.b.c=127.0.0.1
+
+ What happens if the DNS lookup for the incoming IP address yields both
+ 127.0.0.1 and 127.0.0.2 by means of two separate DNS records? Is the
+ condition true because at least one given value was found, or is it false
+ because at least one of the found values was not listed? And how does this
+ affect negated conditions?
+
+ The behaviour of = and & has not been changed; however, the text below
+ documents it more clearly. In addition, two new additional conditions (==
+ and =&) have been added, to permit the "other" behaviour to be configured.
+
+ A DNS lookup may yield more than one record. Thus, the result of the lookup
+ for a dnslists check may yield more than one IP address. The question then
+ arises as to whether all the looked up addresses must be listed, or whether
+ just one is good enough. Both possibilities are provided for:
+
+ . If = or & is used, the condition is true if any one of the looked up
+ IP addresses matches one of the listed addresses. Consider:
+
+ dnslists = a.b.c=127.0.0.1
+
+ If the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is
+ true because 127.0.0.1 matches.
+
+ . If == or =& is used, the condition is true only if every one of the
+ looked up IP addresses matches one of the listed addresses. Consider:
+
+ dnslists = a.b.c==127.0.0.1
+
+ If the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is
+ false because 127.0.0.2 is not listed. You would need to have
+
+ dnslists = a.b.c==127.0.0.1,127.0.0.2
+
+ for the condition to be true.
+
+ When ! is used to negate IP address matching, it inverts the result, giving
+ the precise opposite of the behaviour above. Thus:
+
+ . If != or !& is used, the condition is true if none of the looked up IP
+ addresses matches one of the listed addresses. Consider:
+
+ dnslists = a.b.c!&0.0.0.1
+
+ If the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is
+ false because 127.0.0.1 matches.
+
+ . If !== or !=& is used, the condition is true there is at least one looked
+ up IP address that does not match. Consider:
+
+ dnslists = a.b.c!=&0.0.0.1
+
+ If the DNS lookup yields both 127.0.0.1 and 127.0.0.2, the condition is
+ true, because 127.0.0.2 does not match. You would need to have
+
+ dnslists = a.b.c!=&0.0.0.1,0.0.0.2
+
+ for the condition to be false.
+
+ When the DNS lookup yields only a single IP address, there is no difference
+ between = and == and between & and =&.
+
+ 3. Up till now, the only control over which cipher suites GnuTLS uses has been
+ for the cipher algorithms. New options have been added to allow some of the
+ other parameters to be varied. Here is complete documentation for the
+ available features:
+
+ GnuTLS allows the caller to specify separate lists of permitted key
+ exchange methods, main cipher algorithms, and MAC algorithms. These may be
+ used in any combination to form a specific cipher suite. This is unlike
+ OpenSSL, where complete cipher names can be passed to its control function.
+ GnuTLS also allows a list of acceptable protocols to be supplied.
+
+ For compatibility with OpenSSL, the tls_require_ciphers option can be set
+ to complete cipher suite names such as RSA_ARCFOUR_SHA, but for GnuTLS this
+ option controls only the cipher algorithms. Exim searches each item in the
+ list for the name of an available algorithm. For example, if the list
+ contains RSA_AES_SHA, then AES is recognized, and the behaviour is exactly
+ the same as if just AES were given.
+
+ There are additional options called gnutls_require_kx, gnutls_require_mac,
+ and gnutls_require_protocols that can be used to restrict the key exchange
+ methods, MAC algorithms, and protocols, respectively. These options are
+ ignored if OpenSSL is in use.
+
+ All four options are available as global options, controlling how Exim
+ behaves as a server, and also as options of the smtp transport, controlling
+ how Exim behaves as a client. All the values are string expanded. After
+ expansion, the values must be colon-separated lists, though the separator
+ can be changed in the usual way.
+
+ Each of the four lists starts out with a default set of algorithms. If the
+ first item in one of the "require" options does _not_ start with an
+ exclamation mark, all the default items are deleted. In this case, only
+ those that are explicitly specified can be used. If the first item in one
+ of the "require" items _does_ start with an exclamation mark, the defaults
+ are left on the list.
+
+ Then, any item that starts with an exclamation mark causes the relevant
+ entry to be removed from the list, and any item that does not start with an
+ exclamation mark causes a new entry to be added to the list. Unrecognized
+ items in the list are ignored. Thus:
+
+ tls_require_ciphers = !ARCFOUR
+
+ allows all the defaults except ARCFOUR, whereas
+
+ tls_require_ciphers = AES : 3DES
+
+ allows only cipher suites that use AES or 3DES. For tls_require_ciphers
+ the recognized names are AES_256, AES_128, AES (both of the preceding),
+ 3DES, ARCFOUR_128, ARCFOUR_40, and ARCFOUR (both of the preceding). The
+ default list does not contain all of these; it just has AES_256, AES_128,
+ 3DES, and ARCFOUR_128.
+
+ For gnutls_require_kx, the recognized names are DHE_RSA, RSA (which
+ includes DHE_RSA), DHE_DSS, and DHE (which includes both DHE_RSA and
+ DHE_DSS). The default list contains RSA, DHE_DSS, DHE_RSA.
+
+ For gnutls_require_mac, the recognized names are SHA (synonym SHA1), and
+ MD5. The default list contains SHA, MD5.
+
+ For gnutls_require_protocols, the recognized names are TLS1 and SSL3.
+ The default list contains TLS1, SSL3.
+
+ In a server, the order of items in these lists is unimportant. The server
+ will advertise the availability of all the relevant cipher suites. However,
+ in a client, the order in the tls_require_ciphers list specifies a
+ preference order for the cipher algorithms. The first one in the client's
+ list that is also advertised by the server is tried first.
+
+ 4. There is a new compile-time option called ENABLE_DISABLE_FSYNC. You must
+ not set this option unless you really, really, really understand what you
+ are doing. No pre-compiled distributions of Exim should ever set this
+ option. When it is set, Exim compiles a runtime option called
+ disable_fsync. If this is set true, Exim no longer calls fsync() to force
+ updated files' data to be written to disc. Unexpected events such as
+ crashes and power outages may cause data to be lost or scrambled. Beware.
+
+ When ENABLE_DISABLE_FSYNC is not set, a reference to disable_fsync in a
+ runtime configuration generates an "unknown option" error.
+
+ 5. There is a new variable called $smtp_count_at_connection_start. The name
+ is deliberately long, in order to emphasize what the contents are. This
+ variable is set greater than zero only in processes spawned by the Exim
+ daemon for handling incoming SMTP connections. When the daemon accepts a
+ new connection, it increments this variable. A copy of the variable is
+ passed to the child process that handles the connection, but its value is
+ fixed, and never changes. It is only an approximation of how many incoming
+ connections 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 the variable.
+
+ 6. There's a new control called no_pipelining, which does what its name
+ suggests. It turns off the advertising of the PIPELINING extension to SMTP.
+ To be useful, this control must be obeyed before Exim sends its response to
+ an EHLO command. Therefore, it should normally appear in an ACL controlled
+ by acl_smtp_connect or acl_smtp_helo.
+
+ 7. There are two new variables called $sending_ip_address and $sending_port.
+ These are set whenever an SMTP connection to another host has been set up,
+ and they contain the IP address and port of the local interface that is
+ being used. They are of interest only on hosts that have more than on IP
+ address that want to take on different personalities depending on which one
+ is being used.
+
+ 8. The expansion of the helo_data option in the smtp transport now happens
+ after the connection to the server has been made. This means that it can
+ use the value of $sending_ip_address (see 7 above) to vary the text of the
+ message. For example, if you want the string that is used for helo_data to
+ be obtained by a DNS lookup of the interface address, you could use this:
+
+ helo_data = ${lookup dnsdb{ptr=$sending_ip_address}{$value}\
+ {$primary_hostname}}
+
+ The use of helo_data applies both to sending messages and when doing
+ callouts.
+
+ 9. There is a new expansion operator ${rfc2047d: that decodes strings that
+ are encoded as per RFC 2047. Binary zero bytes are replaced by question
+ marks. Characters are converted into the character set defined by
+ headers_charset. Overlong RFC 2047 "words" are not recognized unless
+ check_rfc2047_length is set false.
+
+10. There is a new log selector called "pid", which causes the current process
+ id to be added to every log line, in square brackets, immediately after the
+ time and date.
+
+11. Exim has been modified so that it flushes SMTP output before implementing
+ a delay in an ACL. It also flushes the output before performing a callout,
+ as this can take a substantial time. These behaviours can be disabled by
+ obeying control = no_delay_flush or control = no_callout_flush,
+ respectively, at some earlier stage of the connection. The effect of the
+ new default behaviour is to disable the PIPELINING optimization in these
+ situations, in order to avoid unexpected timeouts in clients.
+
+12. There are two new expansion conditions that iterate over a list. They are
+ called forany and forall, and they are used like this:
+
+ ${if forany{<a list>}{<a condition>}{<yes-string>}{<no-string>}}
+ ${if forall{<a list>}{<a condition>}{<yes-string>}{<no-string>}}
+
+ The first argument is expanded, and the result is treated as a list. By
+ default, the list separator is a colon, but it can be changed by the normal
+ method. The second argument is interpreted as a condition that is to be
+ applied to each item in the list in turn. During the interpretation of the
+ condition, the current list item is placed in a variable called $item.
+
+ - For forany, interpretation stops if the condition is true for any item,
+ and the yes-string is then expanded. If the condition is false for all
+ items in the list, the no-string is expanded.
+
+ - For forall, interpration stops if the condition is false for any item,
+ and the no-string is then expanded. If the condition is true for all
+ items in the list, the yes-string is expanded.
+
+ 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:
+
+ ${if forany{<, $recipients}{match{$item}{^user3@}}{yes}{no}}
+
+ Outside a forany/forall condition, the value of $item is an empty string.
+ Its value is saved and restored while forany/forall is being processed, to
+ enable these expansion items to be nested.
+
+13. There's a new global option called dsn_from that can be used to vary the
+ contents of From: lines in bounces and other automatically generated
+ messages ("delivery status notifications" - hence the name of the option).
+ The default setting is:
+
+ dsn_from = Mail Delivery System <Mailer-Daemon@$qualify_domain>
+
+ The value is expanded every time it is needed. If the expansion fails, a
+ panic is logged, and the default setting is used.
+
+14. The smtp transport has a new option called hosts_avoid_pipelining. It can
+ be used to suppress the use of PIPELINING to certain hosts, while still
+ supporting the other SMTP extensions (cf hosts_avoid_tls).
+
+15. By default, exigrep does case-insensitive matches. There is now a -I option
+ that makes it case-sensitive. This may give a performance improvement when
+ searching large log files. Without -I, the Perl pattern matches use the /i
+ option; with -I they don't. In both cases it is possible to change the case
+ sensitivity within the pattern using (?i) or (?-i).
+
+16. A number of new features have been added to string expansions to make it
+ easier to process lists of items, typically addresses. These are as
+ follows:
+
+ * ${addresses:<string>}
+
+ The string (after expansion) is interpreted as a list of addresses in RFC
+ 2822 format, such as can be found in a To: or Cc: header line. The
+ operative address (local-part@domain) is extracted from each item, and the
+ result of the expansion is a colon-separated list, with appropriate
+ doubling of colons should any happen to be present in the email addresses.
+ Syntactically invalid RFC2822 address items are omitted from the output.
+
+ It is possible to specify a character other than colon for the output
+ separator by starting the string with > followed by the new separator
+ character. For example:
+
+ ${addresses:>& The Boss <ceo@up.stairs>, sec@base.ment (dogsbody)}
+
+ expands to "ceo@up.stairs&sec@base.ment". Compare ${address (singular),
+ which extracts the working address from a single RFC2822 address.
+
+ * ${map{<string1>}{<string2>}}
+
+ After expansion, <string1> 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 <string2> is expanded
+ and added to the output as an item in a new list. The separator used for
+ the output list is the same as the one used for the input, but is not
+ included in the output. For example:
+
+ ${map{a:b:c}{[$item]}} ${map{<- x-y-z}{($item)}}
+
+ expands to "[a]:[b]:[c] (x)-(y)-(z)". At the end of the expansion, the
+ value of $item is restored to what it was before.
+
+ * ${filter{<string1>}{<condition>}}
+
+ After expansion, <string1> 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
+ 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 is not included in the output. For example:
+
+ ${filter{a:b:c}{!eq{$item}{b}}
+
+ yields "a:c". At the end of the expansion, the value of $item is restored
+ to what it was before.
+
+ * ${reduce{<string1>}{<string2>}{<string3>}}
+
+ The ${reduce expansion operation reduces a list to a single, scalar string.
+ After expansion, <string1> is interpreted as a list, colon-separated by
+ default, but the separator can be changed in the usual way. Then <string2>
+ is expanded and assigned to the $value variable. After this, each item in
+ the <string1> list is assigned to $item in turn, and <string3> is expanded
+ for each of them. The result of that expansion is assigned to $value before
+ the next iteration. When the end of the list is reached, the final value of
+ $value is added to the expansion string. The ${reduce expansion item can be
+ used in a number of ways. For example, to add up a list of numbers:
+
+ ${reduce {<, 1,2,3}{0}{${eval:$value+$item}}}
+
+ The result of that expansion would be "6". The maximum of a list of numbers
+ can be found:
+
+ ${reduce {3:0:9:4:6}{0}{${if >{$item}{$value}{$item}{$value}}}}
+
+ At the end of a ${reduce expansion, the values of $item and $value is
+ restored to what they were before.
+
+17. There's a new ACL modifier called "continue". It does nothing of itself,
+ and processing of the ACL always continues with the next condition or
+ modifier. It is provided so that the side effects of expanding its argument
+ can be used. Typically this would be for updating a database. It is really
+ just a syntactic tidiness, because the following two lines have the same
+ effect:
+
+ continue = <some expansion>
+ condition = ${if eq{0}{<some expansion>}{true}{true}}
+
+18. It is now possible to use newline and other control characters (those with
+ values less than 32, plus DEL) as separators in lists. Such separators must
+ be provided literally at the time the list is processed, but the string
+ expansion that happens first means that you can write them using normal
+ escape sequences. For example, if a new-line separated list of domains is
+ generated by a lookup, you can now process it directly by a line such as
+ this:
+
+ domains = <\n ${lookup mysql{.....}}
+
+ This avoids having to change the list separator in such data. Unlike
+ printing character separators, which can be included in list items by
+ doubling, it is not possible to include a control character as data when it
+ is set as the separator. Two such characters in succession are interpreted
+ as enclosing an empty list item.
+
+19. The exigrep utility now has a -v option, which inverts the matching
+ condition.
+
+20. The host_find_failed option in the manualroute router can now be set to
+ "ignore". This causes it to completely ignore a host whose IP address
+ cannot be found. If all the hosts in the list are ignored, the behaviour is
+ controlled by the new host_all_ignored option, which takes the same values
+ as host_find_failed, except that it cannot be set to "ignore". Its default
+ is "defer".
+
+
+Version 4.66
+------------
+
+No new features were added to 4.66.
+
+
+Version 4.65
+------------
+
+No new features were added to 4.65.
+
+
+Version 4.64
+------------
+
+ 1. ACL variables can now be given arbitrary names, as long as they start with
+ "acl_c" or "acl_m" (for connection variables and message variables), are at
+ least six characters long, with the sixth character being either a digit or
+ an underscore.
+
+ 2. There is a new ACL modifier called log_reject_target. It makes it possible
+ to specify which logs are used for messages about ACL rejections.
+
+ 3. There is a new authenticator called "dovecot". This is an interface to the
+ authentication facility of the Dovecot POP/IMAP server, which can support a
+ number of authentication methods.
+
+ 4. The variable $message_headers_raw provides a concatenation of all the
+ messages's headers without any decoding. This is in contrast to
+ $message_headers, which does RFC2047 decoding on the header contents.
+
+ 5. In a DNS black list, if two domain names, comma-separated, are given, the
+ second is used first to do an initial check, making use of any IP value
+ restrictions that are set. If there is a match, the first domain is used,
+ without any IP value restrictions, to get the TXT record.
+
+ 6. All authenticators now have a server_condition option.
+
+ 7. There is a new command-line option called -Mset. It is useful only in
+ conjunction with -be (that is, when testing string expansions). It must be
+ followed by a message id; Exim loads the given message from its spool
+ before doing the expansions.
+
+ 8. Another similar new command-line option is called -bem. It operates like
+ -be except that it must be followed by the name of a file that contains a
+ message.
+
+ 9. When an address is delayed because of a 4xx response to a RCPT command, it
+ is now the combination of sender and recipient that is delayed in
+ subsequent queue runs until its retry time is reached.
+
+10. Unary negation and the bitwise logical operators and, or, xor, not, and
+ shift, have been added to the eval: and eval10: expansion items.
+
+11. The variables $interface_address and $interface_port have been renamed
+ as $received_ip_address and $received_port, to make it clear that they
+ relate to message reception rather than delivery. (The old names remain
+ available for compatibility.)
+
+12. The "message" modifier can now be used on "accept" and "discard" acl verbs
+ to vary the message that is sent when an SMTP command is accepted.
+
+
+Version 4.63
+------------
+
+1. There is a new Boolean option called filter_prepend_home for the redirect
+ router.
+
+2. There is a new acl, set by acl_not_smtp_start, which is run right at the
+ start of receiving a non-SMTP message, before any of the message has been
+ read.
+
+3. When an SMTP error message is specified in a "message" modifier in an ACL,
+ or in a :fail: or :defer: message in a redirect router, Exim now checks the
+ start of the message for an SMTP error code.
+
+4. There is a new parameter for LDAP lookups called "referrals", which takes
+ one of the settings "follow" (the default) or "nofollow".
+
+5. Version 20070721.2 of exipick now included, offering these new options:
+ --reverse
+ After all other sorting options have bee processed, reverse order
+ before displaying messages (-R is synonym).
+ --random
+ Randomize order of matching messages before displaying.
+ --size
+ Instead of displaying the matching messages, display the sum
+ of their sizes.
+ --sort <variable>[,<variable>...]
+ Before displaying matching messages, sort the messages according to
+ each messages value for each variable.
+ --not
+ Negate the value for every test (returns inverse output from the
+ same criteria without --not).
+
+
+Version 4.62
+------------
+
+1. The ${readsocket expansion item now supports Internet domain sockets as well
+ as Unix domain sockets. If the first argument begins "inet:", it must be of
+ the form "inet:host:port". The port is mandatory; it may be a number or the
+ name of a TCP port in /etc/services. The host may be a name, or it may be an
+ IP address. An ip address may optionally be enclosed in square brackets.
+ This is best for IPv6 addresses. For example:
+
+ ${readsocket{inet:[::1]:1234}{<request data>}...
+
+ Only a single host name may be given, but if looking it up yield more than
+ one IP address, they are each tried in turn until a connection is made. Once
+ a connection has been made, the behaviour is as for ${readsocket with a Unix
+ domain socket.
+
+2. If a redirect router sets up file or pipe deliveries for more than one
+ incoming address, and the relevant transport has batch_max set greater than
+ one, a batch delivery now occurs.
+
+3. The appendfile transport has a new option called maildirfolder_create_regex.
+ Its value is a regular expression. For a maildir delivery, this is matched
+ against the maildir directory; if it matches, Exim ensures that a
+ maildirfolder file is created alongside the new, cur, and tmp directories.
+
Version 4.61
------------
-PH/01 There is a new global option called disable_ipv6, which does exactly what
- its name implies. If set true, even if the Exim binary has IPv6 support,
- no IPv6 activities take place. AAAA records are never looked up for host
- names given in manual routing data or elsewhere. AAAA records that are
- received from the DNS as additional data for MX records are ignored. Any
- IPv6 addresses that are listed in local_interfaces, manualroute route
- data, etc. are also ignored. If IP literals are enabled, the ipliteral
- router declines to handle IPv6 literal addresses.
-
-PH/02 There are now 20 of each type of ACL variable by default (instead of 10).
- It is also possible to change the numbers by setting ACL_CVARS and/or
- ACL_MVARS in Local/Makefile. Backward compatibility is maintained if you
- upgrade to this release with existing messages containing ACL variable
- settings on the queue. However, going in the other direction
- (downgrading) will not be compatible; the values of ACL variables will be
- lost.
-
-PH/03 If quota_warn_message contains a From: header, Exim now refrains from
- adding the default one. Similarly, if it contains a Reply-To: header, the
- errors_reply_to option, if set, is not used.
+The documentation is up-to-date for the 4.61 release. Major new features since
+the 4.60 release are:
+
+. An option called disable_ipv6, to disable the use of IPv6 completely.
+
+. An increase in the number of ACL variables to 20 of each type.
+
+. A change to use $auth1, $auth2, and $auth3 in authenticators instead of $1,
+ $2, $3, (though those are still set) because the numeric variables get used
+ for other things in complicated expansions.
+
+. The default for rfc1413_query_timeout has been changed from 30s to 5s.
+
+. It is possible to use setclassresources() on some BSD OS to control the
+ resources used in pipe deliveries.
+
+. A new ACL modifier called add_header, which can be used with any verb.
+
+. More errors are detectable in retry rules.
+
+There are a number of other additions too.
Version 4.60
git://git.exim.org / exim.git / blobdiff