1 $Cambridge: exim/doc/doc-txt/NewStuff,v 1.176 2010/06/14 18:51:10 pdp Exp $
6 This file contains descriptions of new features that have been added to Exim.
7 Before a formal release, there may be quite a lot of detail so that people can
8 test from the snapshots or the CVS before the documentation is updated. Once
9 the documentation is updated, this file is reduced to a short list.
15 1. In addition to the existing LDAP and LDAP/SSL ("ldaps") support, there
16 is now LDAP/TLS support, given sufficiently modern OpenLDAP client
17 libraries. The following global options have been added in support of
18 this: ldap_ca_cert_dir, ldap_ca_cert_file, ldap_cert_file, ldap_cert_key,
19 ldap_cipher_suite, ldap_require_cert, ldap_start_tls.
21 2. The pipe transport now takes a boolean option, "freeze_signal", default
22 false. When true, if the external delivery command exits on a signal then
23 Exim will freeze the message in the queue, instead of generating a bounce.
25 3. Log filenames may now use %M as an escape, instead of %D (still available).
26 The %M pattern expands to yyyymm, providing month-level resolution.
32 1. SECURITY FIX: privilege escalation flaw fixed. On Linux (and only Linux)
33 the flaw permitted the Exim run-time user to cause root to append to
34 arbitrary files of the attacker's choosing, with the content based
35 on content supplied by the attacker.
37 2. Exim now supports loading some lookup types at run-time, using your
38 platform's dlopen() functionality. This has limited platform support
39 and the intention is not to support every variant, it's limited to
40 dlopen(). This permits the main Exim binary to not be linked against
41 all the libraries needed for all the lookup types.
47 NOTE: this version is not guaranteed backwards-compatible, please read the
50 1. A new main configuration option, "openssl_options", is available if Exim
51 is built with SSL support provided by OpenSSL. The option allows
52 administrators to specify OpenSSL options to be used on connections;
53 typically this is to set bug compatibility features which the OpenSSL
54 developers have not enabled by default. There may be security
55 consequences for certain options, so these should not be changed
58 2. A new pipe transport option, "permit_coredumps", may help with problem
59 diagnosis in some scenarios. Note that Exim is typically installed as
60 a setuid binary, which on most OSes will inhibit coredumps by default,
61 so that safety mechanism would have to be overriden for this option to
62 be able to take effect.
64 3. ClamAV 0.95 is now required for ClamAV support in Exim, unless
65 Local/Makefile sets: WITH_OLD_CLAMAV_STREAM=yes
66 Note that this switches Exim to use a new API ("INSTREAM") and a future
67 release of ClamAV will remove support for the old API ("STREAM").
69 The av_scanner option, when set to "clamd", now takes an optional third
70 part, "local", which causes Exim to pass a filename to ClamAV instead of
71 the file content. This is the same behaviour as when clamd is pointed at
72 a Unix-domain socket. For example:
74 av_scanner = clamd:192.0.2.3 1234:local
76 ClamAV's ExtendedDetectionInfo response format is now handled.
78 4. There is now a -bmalware option, restricted to admin users. This option
79 takes one parameter, a filename, and scans that file with Exim's
80 malware-scanning framework. This is intended purely as a debugging aid
81 to ensure that Exim's scanning is working, not to replace other tools.
82 Note that the ACL framework is not invoked, so if av_scanner references
83 ACL variables without a fallback then this will fail.
85 5. There is a new expansion operator, "reverse_ip", which will reverse IP
86 addresses; IPv4 into dotted quad, IPv6 into dotted nibble. Examples:
88 ${reverse_ip:192.0.2.4}
90 ${reverse_ip:2001:0db8:c42:9:1:abcd:192.0.2.3}
91 -> 3.0.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2
93 6. There is a new ACL control called "debug", to enable debug logging.
94 This allows selective logging of certain incoming transactions within
95 production environments, with some care. It takes two options, "tag"
96 and "opts"; "tag" is included in the filename of the log and "opts"
97 is used as per the -d<options> command-line option. Examples, which
98 don't all make sense in all contexts:
101 control = debug/tag=.$sender_host_address
102 control = debug/opts=+expand+acl
103 control = debug/tag=.$message_exim_id/opts=+expand
105 7. It has always been implicit in the design and the documentation that
106 "the Exim user" is not root. src/EDITME said that using root was
107 "very strongly discouraged". This is not enough to keep people from
108 shooting themselves in the foot in days when many don't configure Exim
109 themselves but via package build managers. The security consequences of
110 running various bits of network code are severe if there should be bugs in
111 them. As such, the Exim user may no longer be root. If configured
112 statically, Exim will refuse to build. If configured as ref:user then Exim
113 will exit shortly after start-up. If you must shoot yourself in the foot,
114 then henceforth you will have to maintain your own local patches to strip
117 8. There is a new expansion operator, bool_lax{}. Where bool{} uses the ACL
118 condition logic to determine truth/failure and will fail to expand many
119 strings, bool_lax{} uses the router condition logic, where most strings
121 Note: bool{00} is false, bool_lax{00} is true.
123 9. Routers now support multiple "condition" tests,
125 10. There is now a runtime configuration option "tcp_wrappers_daemon_name".
126 Setting this allows an admin to define which entry in the tcpwrappers
127 config file will be used to control access to the daemon. This option
128 is only available when Exim is built with USE_TCP_WRAPPERS. The
129 default value is set at build time using the TCP_WRAPPERS_DAEMON_NAME
132 11. [POSSIBLE CONFIG BREAKAGE] The default value for system_filter_user is now
133 the Exim run-time user, instead of root.
135 12. [POSSIBLE CONFIG BREAKAGE] ALT_CONFIG_ROOT_ONLY is no longer optional and
136 is forced on. This is mitigated by the new build option
137 TRUSTED_CONFIG_LIST which defines a list of configuration files which
138 are trusted; one per line. If a config file is owned by root and matches
139 a pathname in the list, then it may be invoked by the Exim build-time
140 user without Exim relinquishing root privileges.
142 13. [POSSIBLE CONFIG BREAKAGE] The Exim user is no longer automatically
143 trusted to supply -D<Macro[=Value]> overrides on the command-line. Going
144 forward, we recommend using TRUSTED_CONFIG_LIST with shim configs that
145 include the main config. As a transition mechanism, we are temporarily
146 providing a work-around: the new build option WHITELIST_D_MACROS provides
147 a colon-separated list of macro names which may be overriden by the Exim
148 run-time user. The values of these macros are constrained to the regex
149 ^[A-Za-z0-9_/.-]*$ (which explicitly does allow for empty values).
155 1. TWO SECURITY FIXES: one relating to mail-spools which are globally
156 writable, the other to locking of MBX folders (not mbox).
158 2. MySQL stored procedures are now supported.
160 3. The dkim_domain transport option is now a list, not a single string, and
161 messages will be signed for each element in the list (discarding
164 4. The 4.70 release unexpectedly changed the behaviour of dnsdb TXT lookups
165 in the presence of multiple character strings within the RR. Prior to 4.70,
166 only the first string would be returned. The dnsdb lookup now, by default,
167 preserves the pre-4.70 semantics, but also now takes an extended output
168 separator specification. The separator can be followed by a semicolon, to
169 concatenate the individual text strings together with no join character,
170 or by a comma and a second separator character, in which case the text
171 strings within a TXT record are joined on that second character.
172 Administrators are reminded that DNS provides no ordering guarantees
173 between multiple records in an RRset. For example:
175 foo.example. IN TXT "a" "b" "c"
176 foo.example. IN TXT "d" "e" "f"
178 ${lookup dnsdb{>/ txt=foo.example}} -> "a/d"
179 ${lookup dnsdb{>/; txt=foo.example}} -> "def/abc"
180 ${lookup dnsdb{>/,+ txt=foo.example}} -> "a+b+c/d+e+f"
186 1. Native DKIM support without an external library.
187 (Note that if no action to prevent it is taken, a straight upgrade will
188 result in DKIM verification of all signed incoming emails. See spec
189 for details on conditionally disabling)
191 2. Experimental DCC support via dccifd (contributed by Wolfgang Breyha).
193 3. There is now a bool{} expansion condition which maps certain strings to
194 true/false condition values (most likely of use in conjunction with the
195 and{} expansion operator).
197 4. The $spam_score, $spam_bar and $spam_report variables are now available
200 5. exim -bP now supports "macros", "macro_list" or "macro MACRO_NAME" as
201 options, provided that Exim is invoked by an admin_user.
203 6. There is a new option gnutls_compat_mode, when linked against GnuTLS,
204 which increases compatibility with older clients at the cost of decreased
205 security. Don't set this unless you need to support such clients.
207 7. There is a new expansion operator, ${randint:...} which will produce a
208 "random" number less than the supplied integer. This randomness is
209 not guaranteed to be cryptographically strong, but depending upon how
210 Exim was built may be better than the most naive schemes.
212 8. Exim now explicitly ensures that SHA256 is available when linked against
215 9. The transport_filter_timeout option now applies to SMTP transports too.
221 1. Preliminary DKIM support in Experimental.
227 1. The body_linecount and body_zerocount C variables are now exported in the
230 2. When a dnslists lookup succeeds, the key that was looked up is now placed
231 in $dnslist_matched. When the key is an IP address, it is not reversed in
232 this variable (though it is, of course, in the actual lookup). In simple
235 deny dnslists = spamhaus.example
237 the key is also available in another variable (in this case,
238 $sender_host_address). In more complicated cases, however, this is not
239 true. For example, using a data lookup might generate a dnslists lookup
242 deny dnslists = spamhaus.example/<|192.168.1.2|192.168.6.7|...
244 If this condition succeeds, the value in $dnslist_matched might be
245 192.168.6.7 (for example).
247 3. Authenticators now have a client_condition option. When Exim is running as
248 a client, it skips an authenticator whose client_condition expansion yields
249 "0", "no", or "false". This can be used, for example, to skip plain text
250 authenticators when the connection is not encrypted by a setting such as:
252 client_condition = ${if !eq{$tls_cipher}{}}
254 Note that the 4.67 documentation states that $tls_cipher contains the
255 cipher used for incoming messages. In fact, during SMTP delivery, it
256 contains the cipher used for the delivery. The same is true for
259 4. There is now a -Mvc <message-id> option, which outputs a copy of the
260 message to the standard output, in RFC 2822 format. The option can be used
261 only by an admin user.
263 5. There is now a /noupdate option for the ratelimit ACL condition. It
264 computes the rate and checks the limit as normal, but it does not update
265 the saved data. This means that, in relevant ACLs, it is possible to lookup
266 the existence of a specified (or auto-generated) ratelimit key without
267 incrementing the ratelimit counter for that key.
269 In order for this to be useful, another ACL entry must set the rate
270 for the same key somewhere (otherwise it will always be zero).
275 # Read the rate; if it doesn't exist or is below the maximum
277 deny ratelimit = 100 / 5m / strict / noupdate
278 log_message = RATE: $sender_rate / $sender_rate_period \
279 (max $sender_rate_limit)
281 [... some other logic and tests...]
283 warn ratelimit = 100 / 5m / strict / per_cmd
284 log_message = RATE UPDATE: $sender_rate / $sender_rate_period \
285 (max $sender_rate_limit)
286 condition = ${if le{$sender_rate}{$sender_rate_limit}}
290 6. The variable $max_received_linelength contains the number of bytes in the
291 longest line that was received as part of the message, not counting the
292 line termination character(s).
294 7. Host lists can now include +ignore_defer and +include_defer, analagous to
295 +ignore_unknown and +include_unknown. These options should be used with
296 care, probably only in non-critical host lists such as whitelists.
298 8. There's a new option called queue_only_load_latch, which defaults true.
299 If set false when queue_only_load is greater than zero, Exim re-evaluates
300 the load for each incoming message in an SMTP session. Otherwise, once one
301 message is queued, the remainder are also.
303 9. There is a new ACL, specified by acl_smtp_notquit, which is run in most
304 cases when an SMTP session ends without sending QUIT. However, when Exim
305 itself is is bad trouble, such as being unable to write to its log files,
306 this ACL is not run, because it might try to do things (such as write to
307 log files) that make the situation even worse.
309 Like the QUIT ACL, this new ACL is provided to make it possible to gather
310 statistics. Whatever it returns (accept or deny) is immaterial. The "delay"
311 modifier is forbidden in this ACL.
313 When the NOTQUIT ACL is running, the variable $smtp_notquit_reason is set
314 to a string that indicates the reason for the termination of the SMTP
315 connection. The possible values are:
317 acl-drop Another ACL issued a "drop" command
318 bad-commands Too many unknown or non-mail commands
319 command-timeout Timeout while reading SMTP commands
320 connection-lost The SMTP connection has been lost
321 data-timeout Timeout while reading message data
322 local-scan-error The local_scan() function crashed
323 local-scan-timeout The local_scan() function timed out
324 signal-exit SIGTERM or SIGINT
325 synchronization-error SMTP synchronization error
326 tls-failed TLS failed to start
328 In most cases when an SMTP connection is closed without having received
329 QUIT, Exim sends an SMTP response message before actually closing the
330 connection. With the exception of acl-drop, the default message can be
331 overridden by the "message" modifier in the NOTQUIT ACL. In the case of a
332 "drop" verb in another ACL, it is the message from the other ACL that is
335 10. For MySQL and PostgreSQL lookups, it is now possible to specify a list of
336 servers with individual queries. This is done by starting the query with
337 "servers=x:y:z;", where each item in the list may take one of two forms:
339 (1) If it is just a host name, the appropriate global option (mysql_servers
340 or pgsql_servers) is searched for a host of the same name, and the
341 remaining parameters (database, user, password) are taken from there.
343 (2) If it contains any slashes, it is taken as a complete parameter set.
345 The list of servers is used in exactly the same was as the global list.
346 Once a connection to a server has happened and a query has been
347 successfully executed, processing of the lookup ceases.
349 This feature is intended for use in master/slave situations where updates
350 are occurring, and one wants to update a master rather than a slave. If the
351 masters are in the list for reading, you might have:
353 mysql_servers = slave1/db/name/pw:slave2/db/name/pw:master/db/name/pw
355 In an updating lookup, you could then write
357 ${lookup mysql{servers=master; UPDATE ...}
359 If, on the other hand, the master is not to be used for reading lookups:
361 pgsql_servers = slave1/db/name/pw:slave2/db/name/pw
363 you can still update the master by
365 ${lookup pgsql{servers=master/db/name/pw; UPDATE ...}
367 11. The message_body_newlines option (default FALSE, for backwards
368 compatibility) can be used to control whether newlines are present in
369 $message_body and $message_body_end. If it is FALSE, they are replaced by
376 1. There is a new log selector called smtp_no_mail, which is not included in
377 the default setting. When it is set, a line is written to the main log
378 whenever an accepted SMTP connection terminates without having issued a
381 2. When an item in a dnslists list is followed by = and & and a list of IP
382 addresses, the behaviour was not clear when the lookup returned more than
383 one IP address. This has been solved by the addition of == and =& for "all"
384 rather than the default "any" matching.
386 3. Up till now, the only control over which cipher suites GnuTLS uses has been
387 for the cipher algorithms. New options have been added to allow some of the
388 other parameters to be varied.
390 4. There is a new compile-time option called ENABLE_DISABLE_FSYNC. When it is
391 set, Exim compiles a runtime option called disable_fsync.
393 5. There is a new variable called $smtp_count_at_connection_start.
395 6. There's a new control called no_pipelining.
397 7. There are two new variables called $sending_ip_address and $sending_port.
398 These are set whenever an SMTP connection to another host has been set up.
400 8. The expansion of the helo_data option in the smtp transport now happens
401 after the connection to the server has been made.
403 9. There is a new expansion operator ${rfc2047d: that decodes strings that
404 are encoded as per RFC 2047.
406 10. There is a new log selector called "pid", which causes the current process
407 id to be added to every log line, in square brackets, immediately after the
410 11. Exim has been modified so that it flushes SMTP output before implementing
411 a delay in an ACL. It also flushes the output before performing a callout,
412 as this can take a substantial time. These behaviours can be disabled by
413 obeying control = no_delay_flush or control = no_callout_flush,
414 respectively, at some earlier stage of the connection.
416 12. There are two new expansion conditions that iterate over a list. They are
417 called forany and forall.
419 13. There's a new global option called dsn_from that can be used to vary the
420 contents of From: lines in bounces and other automatically generated
421 messages ("delivery status notifications" - hence the name of the option).
423 14. The smtp transport has a new option called hosts_avoid_pipelining.
425 15. By default, exigrep does case-insensitive matches. There is now a -I option
426 that makes it case-sensitive.
428 16. A number of new features ("addresses", "map", "filter", and "reduce") have
429 been added to string expansions to make it easier to process lists of
430 items, typically addresses.
432 17. There's a new ACL modifier called "continue". It does nothing of itself,
433 and processing of the ACL always continues with the next condition or
434 modifier. It is provided so that the side effects of expanding its argument
437 18. It is now possible to use newline and other control characters (those with
438 values less than 32, plus DEL) as separators in lists.
440 19. The exigrep utility now has a -v option, which inverts the matching
443 20. The host_find_failed option in the manualroute router can now be set to
450 No new features were added to 4.66.
456 No new features were added to 4.65.
462 1. ACL variables can now be given arbitrary names, as long as they start with
463 "acl_c" or "acl_m" (for connection variables and message variables), are at
464 least six characters long, with the sixth character being either a digit or
467 2. There is a new ACL modifier called log_reject_target. It makes it possible
468 to specify which logs are used for messages about ACL rejections.
470 3. There is a new authenticator called "dovecot". This is an interface to the
471 authentication facility of the Dovecot POP/IMAP server, which can support a
472 number of authentication methods.
474 4. The variable $message_headers_raw provides a concatenation of all the
475 messages's headers without any decoding. This is in contrast to
476 $message_headers, which does RFC2047 decoding on the header contents.
478 5. In a DNS black list, if two domain names, comma-separated, are given, the
479 second is used first to do an initial check, making use of any IP value
480 restrictions that are set. If there is a match, the first domain is used,
481 without any IP value restrictions, to get the TXT record.
483 6. All authenticators now have a server_condition option.
485 7. There is a new command-line option called -Mset. It is useful only in
486 conjunction with -be (that is, when testing string expansions). It must be
487 followed by a message id; Exim loads the given message from its spool
488 before doing the expansions.
490 8. Another similar new command-line option is called -bem. It operates like
491 -be except that it must be followed by the name of a file that contains a
494 9. When an address is delayed because of a 4xx response to a RCPT command, it
495 is now the combination of sender and recipient that is delayed in
496 subsequent queue runs until its retry time is reached.
498 10. Unary negation and the bitwise logical operators and, or, xor, not, and
499 shift, have been added to the eval: and eval10: expansion items.
501 11. The variables $interface_address and $interface_port have been renamed
502 as $received_ip_address and $received_port, to make it clear that they
503 relate to message reception rather than delivery. (The old names remain
504 available for compatibility.)
506 12. The "message" modifier can now be used on "accept" and "discard" acl verbs
507 to vary the message that is sent when an SMTP command is accepted.
513 1. There is a new Boolean option called filter_prepend_home for the redirect
516 2. There is a new acl, set by acl_not_smtp_start, which is run right at the
517 start of receiving a non-SMTP message, before any of the message has been
520 3. When an SMTP error message is specified in a "message" modifier in an ACL,
521 or in a :fail: or :defer: message in a redirect router, Exim now checks the
522 start of the message for an SMTP error code.
524 4. There is a new parameter for LDAP lookups called "referrals", which takes
525 one of the settings "follow" (the default) or "nofollow".
527 5. Version 20070721.2 of exipick now included, offering these new options:
529 After all other sorting options have bee processed, reverse order
530 before displaying messages (-R is synonym).
532 Randomize order of matching messages before displaying.
534 Instead of displaying the matching messages, display the sum
536 --sort <variable>[,<variable>...]
537 Before displaying matching messages, sort the messages according to
538 each messages value for each variable.
540 Negate the value for every test (returns inverse output from the
541 same criteria without --not).
547 1. The ${readsocket expansion item now supports Internet domain sockets as well
548 as Unix domain sockets. If the first argument begins "inet:", it must be of
549 the form "inet:host:port". The port is mandatory; it may be a number or the
550 name of a TCP port in /etc/services. The host may be a name, or it may be an
551 IP address. An ip address may optionally be enclosed in square brackets.
552 This is best for IPv6 addresses. For example:
554 ${readsocket{inet:[::1]:1234}{<request data>}...
556 Only a single host name may be given, but if looking it up yield more than
557 one IP address, they are each tried in turn until a connection is made. Once
558 a connection has been made, the behaviour is as for ${readsocket with a Unix
561 2. If a redirect router sets up file or pipe deliveries for more than one
562 incoming address, and the relevant transport has batch_max set greater than
563 one, a batch delivery now occurs.
565 3. The appendfile transport has a new option called maildirfolder_create_regex.
566 Its value is a regular expression. For a maildir delivery, this is matched
567 against the maildir directory; if it matches, Exim ensures that a
568 maildirfolder file is created alongside the new, cur, and tmp directories.
574 The documentation is up-to-date for the 4.61 release. Major new features since
575 the 4.60 release are:
577 . An option called disable_ipv6, to disable the use of IPv6 completely.
579 . An increase in the number of ACL variables to 20 of each type.
581 . A change to use $auth1, $auth2, and $auth3 in authenticators instead of $1,
582 $2, $3, (though those are still set) because the numeric variables get used
583 for other things in complicated expansions.
585 . The default for rfc1413_query_timeout has been changed from 30s to 5s.
587 . It is possible to use setclassresources() on some BSD OS to control the
588 resources used in pipe deliveries.
590 . A new ACL modifier called add_header, which can be used with any verb.
592 . More errors are detectable in retry rules.
594 There are a number of other additions too.
600 The documentation is up-to-date for the 4.60 release. Major new features since
601 the 4.50 release are:
603 . Support for SQLite.
605 . Support for IGNOREQUOTA in LMTP.
607 . Extensions to the "submission mode" features.
609 . Support for Client SMTP Authorization (CSA).
611 . Support for ratelimiting hosts and users.
613 . New expansion items to help with the BATV "prvs" scheme.
615 . A "match_ip" condition, that matches an IP address against a list.
617 There are many more minor changes.