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.
14 1. New options for the ratelimit ACL condition: /count= and /unique=.
15 The /noupdate option has been replaced by a /readonly option.
21 1. The global option "dns_use_edns0" may be set to coerce EDNS0 usage on
22 or off in the resolver library.
28 1. In addition to the existing LDAP and LDAP/SSL ("ldaps") support, there
29 is now LDAP/TLS support, given sufficiently modern OpenLDAP client
30 libraries. The following global options have been added in support of
31 this: ldap_ca_cert_dir, ldap_ca_cert_file, ldap_cert_file, ldap_cert_key,
32 ldap_cipher_suite, ldap_require_cert, ldap_start_tls.
34 2. The pipe transport now takes a boolean option, "freeze_signal", default
35 false. When true, if the external delivery command exits on a signal then
36 Exim will freeze the message in the queue, instead of generating a bounce.
38 3. Log filenames may now use %M as an escape, instead of %D (still available).
39 The %M pattern expands to yyyymm, providing month-level resolution.
41 4. The $message_linecount variable is now updated for the maildir_tag option,
42 in the same way as $message_size, to reflect the real number of lines,
43 including any header additions or removals from transport.
45 5. When contacting a pool of SpamAssassin servers configured in spamd_address,
46 Exim now selects entries randomly, to better scale in a cluster setup.
52 1. SECURITY FIX: privilege escalation flaw fixed. On Linux (and only Linux)
53 the flaw permitted the Exim run-time user to cause root to append to
54 arbitrary files of the attacker's choosing, with the content based
55 on content supplied by the attacker.
57 2. Exim now supports loading some lookup types at run-time, using your
58 platform's dlopen() functionality. This has limited platform support
59 and the intention is not to support every variant, it's limited to
60 dlopen(). This permits the main Exim binary to not be linked against
61 all the libraries needed for all the lookup types.
67 NOTE: this version is not guaranteed backwards-compatible, please read the
70 1. A new main configuration option, "openssl_options", is available if Exim
71 is built with SSL support provided by OpenSSL. The option allows
72 administrators to specify OpenSSL options to be used on connections;
73 typically this is to set bug compatibility features which the OpenSSL
74 developers have not enabled by default. There may be security
75 consequences for certain options, so these should not be changed
78 2. A new pipe transport option, "permit_coredumps", may help with problem
79 diagnosis in some scenarios. Note that Exim is typically installed as
80 a setuid binary, which on most OSes will inhibit coredumps by default,
81 so that safety mechanism would have to be overridden for this option to
82 be able to take effect.
84 3. ClamAV 0.95 is now required for ClamAV support in Exim, unless
85 Local/Makefile sets: WITH_OLD_CLAMAV_STREAM=yes
86 Note that this switches Exim to use a new API ("INSTREAM") and a future
87 release of ClamAV will remove support for the old API ("STREAM").
89 The av_scanner option, when set to "clamd", now takes an optional third
90 part, "local", which causes Exim to pass a filename to ClamAV instead of
91 the file content. This is the same behaviour as when clamd is pointed at
92 a Unix-domain socket. For example:
94 av_scanner = clamd:192.0.2.3 1234:local
96 ClamAV's ExtendedDetectionInfo response format is now handled.
98 4. There is now a -bmalware option, restricted to admin users. This option
99 takes one parameter, a filename, and scans that file with Exim's
100 malware-scanning framework. This is intended purely as a debugging aid
101 to ensure that Exim's scanning is working, not to replace other tools.
102 Note that the ACL framework is not invoked, so if av_scanner references
103 ACL variables without a fallback then this will fail.
105 5. There is a new expansion operator, "reverse_ip", which will reverse IP
106 addresses; IPv4 into dotted quad, IPv6 into dotted nibble. Examples:
108 ${reverse_ip:192.0.2.4}
110 ${reverse_ip:2001:0db8:c42:9:1:abcd:192.0.2.3}
111 -> 3.0.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2
113 6. There is a new ACL control called "debug", to enable debug logging.
114 This allows selective logging of certain incoming transactions within
115 production environments, with some care. It takes two options, "tag"
116 and "opts"; "tag" is included in the filename of the log and "opts"
117 is used as per the -d<options> command-line option. Examples, which
118 don't all make sense in all contexts:
121 control = debug/tag=.$sender_host_address
122 control = debug/opts=+expand+acl
123 control = debug/tag=.$message_exim_id/opts=+expand
125 7. It has always been implicit in the design and the documentation that
126 "the Exim user" is not root. src/EDITME said that using root was
127 "very strongly discouraged". This is not enough to keep people from
128 shooting themselves in the foot in days when many don't configure Exim
129 themselves but via package build managers. The security consequences of
130 running various bits of network code are severe if there should be bugs in
131 them. As such, the Exim user may no longer be root. If configured
132 statically, Exim will refuse to build. If configured as ref:user then Exim
133 will exit shortly after start-up. If you must shoot yourself in the foot,
134 then henceforth you will have to maintain your own local patches to strip
137 8. There is a new expansion operator, bool_lax{}. Where bool{} uses the ACL
138 condition logic to determine truth/failure and will fail to expand many
139 strings, bool_lax{} uses the router condition logic, where most strings
141 Note: bool{00} is false, bool_lax{00} is true.
143 9. Routers now support multiple "condition" tests,
145 10. There is now a runtime configuration option "tcp_wrappers_daemon_name".
146 Setting this allows an admin to define which entry in the tcpwrappers
147 config file will be used to control access to the daemon. This option
148 is only available when Exim is built with USE_TCP_WRAPPERS. The
149 default value is set at build time using the TCP_WRAPPERS_DAEMON_NAME
152 11. [POSSIBLE CONFIG BREAKAGE] The default value for system_filter_user is now
153 the Exim run-time user, instead of root.
155 12. [POSSIBLE CONFIG BREAKAGE] ALT_CONFIG_ROOT_ONLY is no longer optional and
156 is forced on. This is mitigated by the new build option
157 TRUSTED_CONFIG_LIST which defines a list of configuration files which
158 are trusted; one per line. If a config file is owned by root and matches
159 a pathname in the list, then it may be invoked by the Exim build-time
160 user without Exim relinquishing root privileges.
162 13. [POSSIBLE CONFIG BREAKAGE] The Exim user is no longer automatically
163 trusted to supply -D<Macro[=Value]> overrides on the command-line. Going
164 forward, we recommend using TRUSTED_CONFIG_LIST with shim configs that
165 include the main config. As a transition mechanism, we are temporarily
166 providing a work-around: the new build option WHITELIST_D_MACROS provides
167 a colon-separated list of macro names which may be overridden by the Exim
168 run-time user. The values of these macros are constrained to the regex
169 ^[A-Za-z0-9_/.-]*$ (which explicitly does allow for empty values).
175 1. TWO SECURITY FIXES: one relating to mail-spools which are globally
176 writable, the other to locking of MBX folders (not mbox).
178 2. MySQL stored procedures are now supported.
180 3. The dkim_domain transport option is now a list, not a single string, and
181 messages will be signed for each element in the list (discarding
184 4. The 4.70 release unexpectedly changed the behaviour of dnsdb TXT lookups
185 in the presence of multiple character strings within the RR. Prior to 4.70,
186 only the first string would be returned. The dnsdb lookup now, by default,
187 preserves the pre-4.70 semantics, but also now takes an extended output
188 separator specification. The separator can be followed by a semicolon, to
189 concatenate the individual text strings together with no join character,
190 or by a comma and a second separator character, in which case the text
191 strings within a TXT record are joined on that second character.
192 Administrators are reminded that DNS provides no ordering guarantees
193 between multiple records in an RRset. For example:
195 foo.example. IN TXT "a" "b" "c"
196 foo.example. IN TXT "d" "e" "f"
198 ${lookup dnsdb{>/ txt=foo.example}} -> "a/d"
199 ${lookup dnsdb{>/; txt=foo.example}} -> "def/abc"
200 ${lookup dnsdb{>/,+ txt=foo.example}} -> "a+b+c/d+e+f"
206 1. Native DKIM support without an external library.
207 (Note that if no action to prevent it is taken, a straight upgrade will
208 result in DKIM verification of all signed incoming emails. See spec
209 for details on conditionally disabling)
211 2. Experimental DCC support via dccifd (contributed by Wolfgang Breyha).
213 3. There is now a bool{} expansion condition which maps certain strings to
214 true/false condition values (most likely of use in conjunction with the
215 and{} expansion operator).
217 4. The $spam_score, $spam_bar and $spam_report variables are now available
220 5. exim -bP now supports "macros", "macro_list" or "macro MACRO_NAME" as
221 options, provided that Exim is invoked by an admin_user.
223 6. There is a new option gnutls_compat_mode, when linked against GnuTLS,
224 which increases compatibility with older clients at the cost of decreased
225 security. Don't set this unless you need to support such clients.
227 7. There is a new expansion operator, ${randint:...} which will produce a
228 "random" number less than the supplied integer. This randomness is
229 not guaranteed to be cryptographically strong, but depending upon how
230 Exim was built may be better than the most naive schemes.
232 8. Exim now explicitly ensures that SHA256 is available when linked against
235 9. The transport_filter_timeout option now applies to SMTP transports too.
241 1. Preliminary DKIM support in Experimental.
247 1. The body_linecount and body_zerocount C variables are now exported in the
250 2. When a dnslists lookup succeeds, the key that was looked up is now placed
251 in $dnslist_matched. When the key is an IP address, it is not reversed in
252 this variable (though it is, of course, in the actual lookup). In simple
255 deny dnslists = spamhaus.example
257 the key is also available in another variable (in this case,
258 $sender_host_address). In more complicated cases, however, this is not
259 true. For example, using a data lookup might generate a dnslists lookup
262 deny dnslists = spamhaus.example/<|192.168.1.2|192.168.6.7|...
264 If this condition succeeds, the value in $dnslist_matched might be
265 192.168.6.7 (for example).
267 3. Authenticators now have a client_condition option. When Exim is running as
268 a client, it skips an authenticator whose client_condition expansion yields
269 "0", "no", or "false". This can be used, for example, to skip plain text
270 authenticators when the connection is not encrypted by a setting such as:
272 client_condition = ${if !eq{$tls_cipher}{}}
274 Note that the 4.67 documentation states that $tls_cipher contains the
275 cipher used for incoming messages. In fact, during SMTP delivery, it
276 contains the cipher used for the delivery. The same is true for
279 4. There is now a -Mvc <message-id> option, which outputs a copy of the
280 message to the standard output, in RFC 2822 format. The option can be used
281 only by an admin user.
283 5. There is now a /noupdate option for the ratelimit ACL condition. It
284 computes the rate and checks the limit as normal, but it does not update
285 the saved data. This means that, in relevant ACLs, it is possible to lookup
286 the existence of a specified (or auto-generated) ratelimit key without
287 incrementing the ratelimit counter for that key.
289 In order for this to be useful, another ACL entry must set the rate
290 for the same key somewhere (otherwise it will always be zero).
295 # Read the rate; if it doesn't exist or is below the maximum
297 deny ratelimit = 100 / 5m / strict / noupdate
298 log_message = RATE: $sender_rate / $sender_rate_period \
299 (max $sender_rate_limit)
301 [... some other logic and tests...]
303 warn ratelimit = 100 / 5m / strict / per_cmd
304 log_message = RATE UPDATE: $sender_rate / $sender_rate_period \
305 (max $sender_rate_limit)
306 condition = ${if le{$sender_rate}{$sender_rate_limit}}
310 6. The variable $max_received_linelength contains the number of bytes in the
311 longest line that was received as part of the message, not counting the
312 line termination character(s).
314 7. Host lists can now include +ignore_defer and +include_defer, analagous to
315 +ignore_unknown and +include_unknown. These options should be used with
316 care, probably only in non-critical host lists such as whitelists.
318 8. There's a new option called queue_only_load_latch, which defaults true.
319 If set false when queue_only_load is greater than zero, Exim re-evaluates
320 the load for each incoming message in an SMTP session. Otherwise, once one
321 message is queued, the remainder are also.
323 9. There is a new ACL, specified by acl_smtp_notquit, which is run in most
324 cases when an SMTP session ends without sending QUIT. However, when Exim
325 itself is is bad trouble, such as being unable to write to its log files,
326 this ACL is not run, because it might try to do things (such as write to
327 log files) that make the situation even worse.
329 Like the QUIT ACL, this new ACL is provided to make it possible to gather
330 statistics. Whatever it returns (accept or deny) is immaterial. The "delay"
331 modifier is forbidden in this ACL.
333 When the NOTQUIT ACL is running, the variable $smtp_notquit_reason is set
334 to a string that indicates the reason for the termination of the SMTP
335 connection. The possible values are:
337 acl-drop Another ACL issued a "drop" command
338 bad-commands Too many unknown or non-mail commands
339 command-timeout Timeout while reading SMTP commands
340 connection-lost The SMTP connection has been lost
341 data-timeout Timeout while reading message data
342 local-scan-error The local_scan() function crashed
343 local-scan-timeout The local_scan() function timed out
344 signal-exit SIGTERM or SIGINT
345 synchronization-error SMTP synchronization error
346 tls-failed TLS failed to start
348 In most cases when an SMTP connection is closed without having received
349 QUIT, Exim sends an SMTP response message before actually closing the
350 connection. With the exception of acl-drop, the default message can be
351 overridden by the "message" modifier in the NOTQUIT ACL. In the case of a
352 "drop" verb in another ACL, it is the message from the other ACL that is
355 10. For MySQL and PostgreSQL lookups, it is now possible to specify a list of
356 servers with individual queries. This is done by starting the query with
357 "servers=x:y:z;", where each item in the list may take one of two forms:
359 (1) If it is just a host name, the appropriate global option (mysql_servers
360 or pgsql_servers) is searched for a host of the same name, and the
361 remaining parameters (database, user, password) are taken from there.
363 (2) If it contains any slashes, it is taken as a complete parameter set.
365 The list of servers is used in exactly the same was as the global list.
366 Once a connection to a server has happened and a query has been
367 successfully executed, processing of the lookup ceases.
369 This feature is intended for use in master/slave situations where updates
370 are occurring, and one wants to update a master rather than a slave. If the
371 masters are in the list for reading, you might have:
373 mysql_servers = slave1/db/name/pw:slave2/db/name/pw:master/db/name/pw
375 In an updating lookup, you could then write
377 ${lookup mysql{servers=master; UPDATE ...}
379 If, on the other hand, the master is not to be used for reading lookups:
381 pgsql_servers = slave1/db/name/pw:slave2/db/name/pw
383 you can still update the master by
385 ${lookup pgsql{servers=master/db/name/pw; UPDATE ...}
387 11. The message_body_newlines option (default FALSE, for backwards
388 compatibility) can be used to control whether newlines are present in
389 $message_body and $message_body_end. If it is FALSE, they are replaced by
396 1. There is a new log selector called smtp_no_mail, which is not included in
397 the default setting. When it is set, a line is written to the main log
398 whenever an accepted SMTP connection terminates without having issued a
401 2. When an item in a dnslists list is followed by = and & and a list of IP
402 addresses, the behaviour was not clear when the lookup returned more than
403 one IP address. This has been solved by the addition of == and =& for "all"
404 rather than the default "any" matching.
406 3. Up till now, the only control over which cipher suites GnuTLS uses has been
407 for the cipher algorithms. New options have been added to allow some of the
408 other parameters to be varied.
410 4. There is a new compile-time option called ENABLE_DISABLE_FSYNC. When it is
411 set, Exim compiles a runtime option called disable_fsync.
413 5. There is a new variable called $smtp_count_at_connection_start.
415 6. There's a new control called no_pipelining.
417 7. There are two new variables called $sending_ip_address and $sending_port.
418 These are set whenever an SMTP connection to another host has been set up.
420 8. The expansion of the helo_data option in the smtp transport now happens
421 after the connection to the server has been made.
423 9. There is a new expansion operator ${rfc2047d: that decodes strings that
424 are encoded as per RFC 2047.
426 10. There is a new log selector called "pid", which causes the current process
427 id to be added to every log line, in square brackets, immediately after the
430 11. Exim has been modified so that it flushes SMTP output before implementing
431 a delay in an ACL. It also flushes the output before performing a callout,
432 as this can take a substantial time. These behaviours can be disabled by
433 obeying control = no_delay_flush or control = no_callout_flush,
434 respectively, at some earlier stage of the connection.
436 12. There are two new expansion conditions that iterate over a list. They are
437 called forany and forall.
439 13. There's a new global option called dsn_from that can be used to vary the
440 contents of From: lines in bounces and other automatically generated
441 messages ("delivery status notifications" - hence the name of the option).
443 14. The smtp transport has a new option called hosts_avoid_pipelining.
445 15. By default, exigrep does case-insensitive matches. There is now a -I option
446 that makes it case-sensitive.
448 16. A number of new features ("addresses", "map", "filter", and "reduce") have
449 been added to string expansions to make it easier to process lists of
450 items, typically addresses.
452 17. There's a new ACL modifier called "continue". It does nothing of itself,
453 and processing of the ACL always continues with the next condition or
454 modifier. It is provided so that the side effects of expanding its argument
457 18. It is now possible to use newline and other control characters (those with
458 values less than 32, plus DEL) as separators in lists.
460 19. The exigrep utility now has a -v option, which inverts the matching
463 20. The host_find_failed option in the manualroute router can now be set to
470 No new features were added to 4.66.
476 No new features were added to 4.65.
482 1. ACL variables can now be given arbitrary names, as long as they start with
483 "acl_c" or "acl_m" (for connection variables and message variables), are at
484 least six characters long, with the sixth character being either a digit or
487 2. There is a new ACL modifier called log_reject_target. It makes it possible
488 to specify which logs are used for messages about ACL rejections.
490 3. There is a new authenticator called "dovecot". This is an interface to the
491 authentication facility of the Dovecot POP/IMAP server, which can support a
492 number of authentication methods.
494 4. The variable $message_headers_raw provides a concatenation of all the
495 messages's headers without any decoding. This is in contrast to
496 $message_headers, which does RFC2047 decoding on the header contents.
498 5. In a DNS black list, if two domain names, comma-separated, are given, the
499 second is used first to do an initial check, making use of any IP value
500 restrictions that are set. If there is a match, the first domain is used,
501 without any IP value restrictions, to get the TXT record.
503 6. All authenticators now have a server_condition option.
505 7. There is a new command-line option called -Mset. It is useful only in
506 conjunction with -be (that is, when testing string expansions). It must be
507 followed by a message id; Exim loads the given message from its spool
508 before doing the expansions.
510 8. Another similar new command-line option is called -bem. It operates like
511 -be except that it must be followed by the name of a file that contains a
514 9. When an address is delayed because of a 4xx response to a RCPT command, it
515 is now the combination of sender and recipient that is delayed in
516 subsequent queue runs until its retry time is reached.
518 10. Unary negation and the bitwise logical operators and, or, xor, not, and
519 shift, have been added to the eval: and eval10: expansion items.
521 11. The variables $interface_address and $interface_port have been renamed
522 as $received_ip_address and $received_port, to make it clear that they
523 relate to message reception rather than delivery. (The old names remain
524 available for compatibility.)
526 12. The "message" modifier can now be used on "accept" and "discard" acl verbs
527 to vary the message that is sent when an SMTP command is accepted.
533 1. There is a new Boolean option called filter_prepend_home for the redirect
536 2. There is a new acl, set by acl_not_smtp_start, which is run right at the
537 start of receiving a non-SMTP message, before any of the message has been
540 3. When an SMTP error message is specified in a "message" modifier in an ACL,
541 or in a :fail: or :defer: message in a redirect router, Exim now checks the
542 start of the message for an SMTP error code.
544 4. There is a new parameter for LDAP lookups called "referrals", which takes
545 one of the settings "follow" (the default) or "nofollow".
547 5. Version 20070721.2 of exipick now included, offering these new options:
549 After all other sorting options have bee processed, reverse order
550 before displaying messages (-R is synonym).
552 Randomize order of matching messages before displaying.
554 Instead of displaying the matching messages, display the sum
556 --sort <variable>[,<variable>...]
557 Before displaying matching messages, sort the messages according to
558 each messages value for each variable.
560 Negate the value for every test (returns inverse output from the
561 same criteria without --not).
567 1. The ${readsocket expansion item now supports Internet domain sockets as well
568 as Unix domain sockets. If the first argument begins "inet:", it must be of
569 the form "inet:host:port". The port is mandatory; it may be a number or the
570 name of a TCP port in /etc/services. The host may be a name, or it may be an
571 IP address. An ip address may optionally be enclosed in square brackets.
572 This is best for IPv6 addresses. For example:
574 ${readsocket{inet:[::1]:1234}{<request data>}...
576 Only a single host name may be given, but if looking it up yield more than
577 one IP address, they are each tried in turn until a connection is made. Once
578 a connection has been made, the behaviour is as for ${readsocket with a Unix
581 2. If a redirect router sets up file or pipe deliveries for more than one
582 incoming address, and the relevant transport has batch_max set greater than
583 one, a batch delivery now occurs.
585 3. The appendfile transport has a new option called maildirfolder_create_regex.
586 Its value is a regular expression. For a maildir delivery, this is matched
587 against the maildir directory; if it matches, Exim ensures that a
588 maildirfolder file is created alongside the new, cur, and tmp directories.
594 The documentation is up-to-date for the 4.61 release. Major new features since
595 the 4.60 release are:
597 . An option called disable_ipv6, to disable the use of IPv6 completely.
599 . An increase in the number of ACL variables to 20 of each type.
601 . A change to use $auth1, $auth2, and $auth3 in authenticators instead of $1,
602 $2, $3, (though those are still set) because the numeric variables get used
603 for other things in complicated expansions.
605 . The default for rfc1413_query_timeout has been changed from 30s to 5s.
607 . It is possible to use setclassresources() on some BSD OS to control the
608 resources used in pipe deliveries.
610 . A new ACL modifier called add_header, which can be used with any verb.
612 . More errors are detectable in retry rules.
614 There are a number of other additions too.
620 The documentation is up-to-date for the 4.60 release. Major new features since
621 the 4.50 release are:
623 . Support for SQLite.
625 . Support for IGNOREQUOTA in LMTP.
627 . Extensions to the "submission mode" features.
629 . Support for Client SMTP Authorization (CSA).
631 . Support for ratelimiting hosts and users.
633 . New expansion items to help with the BATV "prvs" scheme.
635 . A "match_ip" condition, that matches an IP address against a list.
637 There are many more minor changes.