-. $Cambridge: exim/doc/doc-docbook/filter.xfpt,v 1.5 2007/04/11 15:26:09 ph10 Exp $
+. $Cambridge: exim/doc/doc-docbook/filter.xfpt,v 1.6 2007/04/17 13:06:09 ph10 Exp $
. /////////////////////////////////////////////////////////////////////////////
. This is the primary source of the document that describes Exim's filtering
<bookinfo>
<title>Exim's interfaces to mail filtering</title>
<titleabbrev>Exim filtering</titleabbrev>
-<date>31 July</date>
+<date>17 April 2007</date>
<author><firstname>Philip</firstname><surname>Hazel</surname></author>
<authorinitials>PH</authorinitials>
<revhistory><revision>
- <revnumber>4.63</revnumber>
- <date>31 July 2006</date>
+ <revnumber>4.67</revnumber>
+ <date>17 April 2007</date>
<authorinitials>PH</authorinitials>
</revision></revhistory>
-<copyright><year>2006</year><holder>University of Cambridge</holder></copyright>
+<copyright><year>2007</year><holder>University of Cambridge</holder></copyright>
</bookinfo>
.literal off
. /////////////////////////////////////////////////////////////////////////////
-.chapter "Forwarding and filtering in Exim"
+.chapter "Forwarding and filtering in Exim" "CHAPforandfilt"
This document describes the user interfaces to Exim's in-built mail filtering
facilities, and is copyright © University of Cambridge 2007. It
corresponds to Exim version 4.67.
-.section "Introduction"
+.section "Introduction" "SEC00"
Most Unix mail transfer agents (programs that deliver mail) permit individual
users to specify automatic forwarding of their mail, usually by placing a list
of forwarding addresses in a file called &_.forward_& in their home
-.section "Filter operation"
+.section "Filter operation" "SEC01"
It is important to realize that, in Exim, no deliveries are actually made while
a filter or traditional &_.forward_& file is being processed. Running a filter
or processing a traditional &_.forward_& file sets up future delivery
implemented; see the description in section &<<SECTmbox>>& below.
-.section "Installing a filter file"
+.section "Installing a filter file" "SEC02"
A filter file is normally installed under the name &_.forward_& in your home
directory &-- it is distinguished from a conventional &_.forward_& file by its
first line (described below). However, the file name is configurable, and some
filter files.
-.section "Testing an installed filter file"
+.section "Testing an installed filter file" "SEC03"
Testing a filter file before installation cannot find every potential problem;
for example, it does not actually run commands to which messages are piped.
Some &"live"& tests should therefore also be done once a filter is installed.
-.section "Details of filtering commands"
+.section "Details of filtering commands" "SEC04"
The filtering commands for Sieve and Exim filters are completely different in
syntax and semantics. The Sieve mechanism is defined in RFC 3028; in the next
chapter we describe how it is integrated into Exim. The subsequent chapter
chapter on the &(redirect)& router in the full Exim specification.
-.section "Recognition of Sieve filters"
+.section "Recognition of Sieve filters" "SEC05"
A filter file is interpreted as a Sieve filter if its first line is
.code
# Sieve filter
-.section "Saving to specified folders"
+.section "Saving to specified folders" "SEC06"
If the system administrator has set things up as suggested in the Exim
specification, and you use &(keep)& or &(fileinto)& to save a mail into a
folder, absolute files are stored where specified, relative files are stored
-.section "Strings containing header names"
+.section "Strings containing header names" "SEC07"
RFC 3028 does not specify what happens if a string denoting a header field does
not contain a valid header name, for example, it contains a colon. This
implementation generates an error instead of ignoring the header field in order
-.section "Exists test with empty list of headers"
+.section "Exists test with empty list of headers" "SEC08"
The &*exists*& test succeeds only if all the specified headers exist. RFC 3028
does not explicitly specify what happens on an empty list of headers. This
implementation evaluates that condition as true, interpreting the RFC in a
-.section "Header test with invalid MIME encoding in header"
+.section "Header test with invalid MIME encoding in header" "SEC09"
Some MUAs process invalid base64 encoded data, generating junk. Others ignore
junk after seeing an equal sign in base64 encoded data. RFC 2047 does not
specify how to react in this case, other than stating that a client must not
-.section "Address test for multiple addresses per header"
+.section "Address test for multiple addresses per header" "SEC10"
A header may contain multiple addresses. RFC 3028 does not explicitly specify
how to deal with them, but since the address test checks if anything matches
anything else, matching one address suffices to satisfy the condition. That
-.section "Semantics of keep"
+.section "Semantics of keep" "SEC11"
The &(keep)& command is equivalent to
.code
fileinto "inbox";
-.section "Semantics of fileinto"
+.section "Semantics of fileinto" "SEC12"
RFC 3028 does not specify whether &(fileinto)& should try to create a mail
folder if it does not exist. This implementation allows the sysadmin to
configure that aspect using the &(appendfile)& transport options
-.section "Semantics of redirect"
+.section "Semantics of redirect" "SEC13"
Sieve scripts are supposed to be interoperable between servers, so this
implementation does not allow mail to be redirected to unqualified addresses,
because the domain would depend on the system being used. On systems with
-.section "String arguments"
+.section "String arguments" "SEC14"
There has been confusion if the string arguments to &(require)& are to be
matched case-sensitively or not. This implementation matches them with the
match type &(:is)& (default, see section 2.7.1 of the RFC) and the comparator
-.section "Number units"
+.section "Number units" "SEC15"
There is a mistake in RFC 3028: the suffix G denotes gibi-, not tebibyte.
The mistake is obvious, because RFC 3028 specifies G to denote 2^30
(which is gibi, not tebi), and that is what this implementation uses as
-.section "RFC compliance"
+.section "RFC compliance" "SEC16"
Exim requires the first line of a Sieve filter to be
.code
# Sieve filter
This chapter contains a full description of the contents of Exim filter files.
-.section "Format of Exim filter files"
+.section "Format of Exim filter files" "SEC17"
Apart from leading white space, the first text in an Exim filter file must be
.code
# Exim filter
in a filter file.
-.section "Data values in filter commands"
+.section "Data values in filter commands" "SEC18"
There are two ways in which a data value can be input:
.ilist
tests for a run of four dollar characters.
-.section "Some useful general variables"
+.section "Some useful general variables" "SEC19"
A complete list of the available variables is given in the Exim documentation.
This shortened list contains the ones that are most likely to be useful in
personal filter files:
not use &$header_Reply_to$& when you really mean &$header_Reply-to$&.
-.section "User variables"
+.section "User variables" "SEC20"
There are ten user variables with names &$n0$& &-- &$n9$& that can be
incremented by the &(add)& command (see section &<<SECTadd>>&). These can be
used for &"scoring"& messages in various ways. If Exim is configured to run a
entirely up to the individual installation.
-.section "Current directory"
+.section "Current directory" "SEC21"
The contents of your filter file should not make any assumptions about the
current directory. It is best to use absolute paths for file names; you can
normally make use of the &$home$& variable to refer to your home directory. The
-.section "Filter commands"
+.section "Filter commands" "SEC222"
The filter commands that are described in subsequent sections are listed
below, with the section in which they are described in brackets:
-.section "String testing conditions"
+.section "String testing conditions" "SEC23"
There are a number of conditions that operate on text strings, using the words
&"begins"&, &"ends"&, &"is"&, &"contains"& and &"matches"&. If you want to
apply the same test to more than one header line, you can easily concatenate
condition occurs just before it is tested.
-.section "Numeric testing conditions"
+.section "Numeric testing conditions" "SEC24"
The following conditions are available for performing numerical tests:
.display
multiplication by 1024 and 1024x1024 respectively.
-.section "Testing for significant deliveries"
+.section "Testing for significant deliveries" "SEC25"
You can use the &(delivered)& condition to test whether or not any previously
obeyed filter commands have set up a significant delivery. For example:
.code
later processing.
-.section "Testing for error messages"
+.section "Testing for error messages" "SEC26"
The condition &(error_message)& is true if the incoming message is a bounce
(mail delivery error) message. Putting the command
.code
not preceded by &`$`&.
-.section "Testing a list of addresses"
+.section "Testing a list of addresses" "SEC27"
There is a facility for looping through a list of addresses and applying a
condition to each of them. It takes the form
.display
-.section "Alias addresses for the personal condition"
+.section "Alias addresses for the personal condition" "SEC28"
It is quite common for people who have mail accounts on a number of different
systems to forward all their mail to one system, and in this case a check for
personal mail should test all their various mail addresses. To allow for this,
address when testing the contents of header lines.
-.section "Details of the personal condition"
+.section "Details of the personal condition" "SEC29"
The basic &(personal)& test is roughly equivalent to the following:
.code
not error_message and
-.section "Testing delivery status"
+.section "Testing delivery status" "SEC30"
There are two conditions that are intended mainly for use in system filter
files, but which are available in users' filter files as well. The condition
&(first_delivery)& is true if this is the first process that is attempting to
unlikely to be of use in users' filter files.
-.section "Multiple personal mailboxes" "SECTmbox"
+.section "Multiple personal mailboxes" "SECTmbox" "SEC31"
The system administrator can configure Exim so that users can set up variants
on their email addresses and handle them separately. Consult your system
administrator or local documentation to see if this facility is enabled on your
-.section "Ignoring delivery errors"
+.section "Ignoring delivery errors" "SEC43"
As was explained above, filtering just sets up addresses for delivery &-- no
deliveries are actually done while a filter file is active. If any of the
generated addresses subsequently suffers a delivery failure, an error message
-$Cambridge: exim/doc/doc-txt/NewStuff,v 1.145 2007/03/13 15:32:47 ph10 Exp $
+$Cambridge: exim/doc/doc-txt/NewStuff,v 1.146 2007/04/17 13:06:10 ph10 Exp $
New Features in Exim
--------------------
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.
+ MAIL command.
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
+ addresses, the behaviour was not clear when the lookup returned more than
+ one IP address. This has been solved by the addition of == and =& for "all"
+ rather than the defaule "any" matching.
- 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
+ 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.
- for the condition to be false.
+ 4. There is a new compile-time option called ENABLE_DISABLE_FSYNC. When it is
+ set, Exim compiles a runtime option called disable_fsync.
- When the DNS lookup yields only a single IP address, there is no difference
- between = and == and between & and =&.
+ 5. There is a new variable called $smtp_count_at_connection_start.
- 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.
+ 6. There's a new control called no_pipelining.
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.
+ These are set whenever an SMTP connection to another host has been set up.
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.
+ after the connection to the server has been made.
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.
+ are encoded as per RFC 2047.
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
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.
+ respectively, at some earlier stage of the connection.
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 $item is an empty string.
- Its value is saved and restored while forany/forall is being processed, to
- enable these expansion items to be nested.
+ called forany and forall.
13. There's a new global option called dsn_from that can be used to vary the
contents of From: lines in bounces and other automatically generated
messages ("delivery status notifications" - hence the name of the option).
- The default setting is:
- dsn_from = Mail Delivery System <Mailer-Daemon@$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).
+14. The smtp transport has a new option called hosts_avoid_pipelining.
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:
+ that makes it case-sensitive.
- ${map{a:b:c}{[$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.
+16. A number of new features ("addresses", "map", "filter", and "reduce") have
+ been added to string expansions to make it easier to process lists of
+ items, typically addresses.
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}}
+ can be used.
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.
+ values less than 32, plus DEL) as separators in lists.
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".
+ "ignore".
Version 4.66
git://git.exim.org / exim.git / commitdiff