4 This file contains descriptions of new features that have been added to Exim.
5 Before a formal release, there may be quite a lot of detail so that people can
6 test from the snapshots or the CVS before the documentation is updated. Once
7 the documentation is updated, this file is reduced to a short list.
12 1. New authenticator driver, "gsasl". Server-only (at present).
13 This is a SASL interface, licensed under GPL, which can be found at
14 http://www.gnu.org/software/gsasl/.
15 This system does not provide sources of data for authentication, so
16 careful use needs to be made of the conditions in Exim.
18 2. New authenticator driver, "heimdal_gssapi". Server-only.
19 A replacement for using cyrus_sasl with Heimdal, now that $KRB5_KTNAME
20 is no longer honoured for setuid programs by Heimdal. Use the
21 "server_keytab" option to point to the keytab.
23 3. The "pkg-config" system can now be used when building Exim to reference
24 cflags and library information for lookups and authenticators, rather
25 than having to update "CFLAGS", "AUTH_LIBS", "LOOKUP_INCLUDE" and
26 "LOOKUP_LIBS" directly. Similarly for handling the TLS library support
27 without adjusting "TLS_INCLUDE" and "TLS_LIBS".
29 4. New expansion variable $tls_bits.
31 5. New lookup type, "dbmjz". Key is an Exim list, the elements of which will
32 be joined together with ASCII NUL characters to construct the key to pass
33 into the DBM library. Can be used with gsasl to access sasldb2 files as
36 6. OpenSSL now supports TLS1.1 and TLS1.2 with OpenSSL 1.0.1.
38 Avoid release 1.0.1a if you can. Note that the default value of
39 "openssl_options" is no longer "+dont_insert_empty_fragments", as that
40 increased susceptibility to attack. This may still have interoperability
41 implications for very old clients (see version 4.31 change 37) but
42 administrators can choose to make the trade-off themselves and restore
43 compatibility at the cost of session security.
45 7. Use of the new expansion variable $tls_sni in the main configuration option
46 tls_certificate will cause Exim to re-expand the option, if the client
47 sends the TLS Server Name Indication extension, to permit choosing a
48 different certificate; tls_privatekey will also be re-expanded. You must
49 still set these options to expand to valid files when $tls_sni is not set.
51 The SMTP Transport has gained the option tls_sni, which will set a hostname
52 for outbound TLS sessions, and set $tls_sni too.
54 A new log_selector, +tls_sni, has been added, to log received SNI values
57 Currently OpenSSL only.
59 8. The existing "accept_8bitmime" option now defaults to true. This means
60 that Exim is deliberately not strictly RFC compliant. We're following
61 Dan Bernstein's advice in http://cr.yp.to/smtp/8bitmime.html by default.
62 Those who disagree, or know that they are talking to mail servers that,
63 even today, are not 8-bit clean, need to turn off this option.
69 1. New options for the ratelimit ACL condition: /count= and /unique=.
70 The /noupdate option has been replaced by a /readonly option.
72 2. The SMTP transport's protocol option may now be set to "smtps", to
73 use SSL-on-connect outbound.
75 3. New variable $av_failed, set true if the AV scanner deferred; ie, when
76 there is a problem talking to the AV scanner, or the AV scanner running.
78 4. New expansion conditions, "inlist" and "inlisti", which take simple lists
79 and check if the search item is a member of the list. This does not
80 support named lists, but does subject the list part to string expansion.
82 5. Unless the new EXPAND_LISTMATCH_RHS build option is set when Exim was
83 built, Exim no longer performs string expansion on the second string of
84 the match_* expansion conditions: "match_address", "match_domain",
85 "match_ip" & "match_local_part". Named lists can still be used.
91 1. The global option "dns_use_edns0" may be set to coerce EDNS0 usage on
92 or off in the resolver library.
98 1. In addition to the existing LDAP and LDAP/SSL ("ldaps") support, there
99 is now LDAP/TLS support, given sufficiently modern OpenLDAP client
100 libraries. The following global options have been added in support of
101 this: ldap_ca_cert_dir, ldap_ca_cert_file, ldap_cert_file, ldap_cert_key,
102 ldap_cipher_suite, ldap_require_cert, ldap_start_tls.
104 2. The pipe transport now takes a boolean option, "freeze_signal", default
105 false. When true, if the external delivery command exits on a signal then
106 Exim will freeze the message in the queue, instead of generating a bounce.
108 3. Log filenames may now use %M as an escape, instead of %D (still available).
109 The %M pattern expands to yyyymm, providing month-level resolution.
111 4. The $message_linecount variable is now updated for the maildir_tag option,
112 in the same way as $message_size, to reflect the real number of lines,
113 including any header additions or removals from transport.
115 5. When contacting a pool of SpamAssassin servers configured in spamd_address,
116 Exim now selects entries randomly, to better scale in a cluster setup.
122 1. SECURITY FIX: privilege escalation flaw fixed. On Linux (and only Linux)
123 the flaw permitted the Exim run-time user to cause root to append to
124 arbitrary files of the attacker's choosing, with the content based
125 on content supplied by the attacker.
127 2. Exim now supports loading some lookup types at run-time, using your
128 platform's dlopen() functionality. This has limited platform support
129 and the intention is not to support every variant, it's limited to
130 dlopen(). This permits the main Exim binary to not be linked against
131 all the libraries needed for all the lookup types.
137 NOTE: this version is not guaranteed backwards-compatible, please read the
138 items below carefully
140 1. A new main configuration option, "openssl_options", is available if Exim
141 is built with SSL support provided by OpenSSL. The option allows
142 administrators to specify OpenSSL options to be used on connections;
143 typically this is to set bug compatibility features which the OpenSSL
144 developers have not enabled by default. There may be security
145 consequences for certain options, so these should not be changed
148 2. A new pipe transport option, "permit_coredumps", may help with problem
149 diagnosis in some scenarios. Note that Exim is typically installed as
150 a setuid binary, which on most OSes will inhibit coredumps by default,
151 so that safety mechanism would have to be overridden for this option to
152 be able to take effect.
154 3. ClamAV 0.95 is now required for ClamAV support in Exim, unless
155 Local/Makefile sets: WITH_OLD_CLAMAV_STREAM=yes
156 Note that this switches Exim to use a new API ("INSTREAM") and a future
157 release of ClamAV will remove support for the old API ("STREAM").
159 The av_scanner option, when set to "clamd", now takes an optional third
160 part, "local", which causes Exim to pass a filename to ClamAV instead of
161 the file content. This is the same behaviour as when clamd is pointed at
162 a Unix-domain socket. For example:
164 av_scanner = clamd:192.0.2.3 1234:local
166 ClamAV's ExtendedDetectionInfo response format is now handled.
168 4. There is now a -bmalware option, restricted to admin users. This option
169 takes one parameter, a filename, and scans that file with Exim's
170 malware-scanning framework. This is intended purely as a debugging aid
171 to ensure that Exim's scanning is working, not to replace other tools.
172 Note that the ACL framework is not invoked, so if av_scanner references
173 ACL variables without a fallback then this will fail.
175 5. There is a new expansion operator, "reverse_ip", which will reverse IP
176 addresses; IPv4 into dotted quad, IPv6 into dotted nibble. Examples:
178 ${reverse_ip:192.0.2.4}
180 ${reverse_ip:2001:0db8:c42:9:1:abcd:192.0.2.3}
181 -> 3.0.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2
183 6. There is a new ACL control called "debug", to enable debug logging.
184 This allows selective logging of certain incoming transactions within
185 production environments, with some care. It takes two options, "tag"
186 and "opts"; "tag" is included in the filename of the log and "opts"
187 is used as per the -d<options> command-line option. Examples, which
188 don't all make sense in all contexts:
191 control = debug/tag=.$sender_host_address
192 control = debug/opts=+expand+acl
193 control = debug/tag=.$message_exim_id/opts=+expand
195 7. It has always been implicit in the design and the documentation that
196 "the Exim user" is not root. src/EDITME said that using root was
197 "very strongly discouraged". This is not enough to keep people from
198 shooting themselves in the foot in days when many don't configure Exim
199 themselves but via package build managers. The security consequences of
200 running various bits of network code are severe if there should be bugs in
201 them. As such, the Exim user may no longer be root. If configured
202 statically, Exim will refuse to build. If configured as ref:user then Exim
203 will exit shortly after start-up. If you must shoot yourself in the foot,
204 then henceforth you will have to maintain your own local patches to strip
207 8. There is a new expansion operator, bool_lax{}. Where bool{} uses the ACL
208 condition logic to determine truth/failure and will fail to expand many
209 strings, bool_lax{} uses the router condition logic, where most strings
211 Note: bool{00} is false, bool_lax{00} is true.
213 9. Routers now support multiple "condition" tests,
215 10. There is now a runtime configuration option "tcp_wrappers_daemon_name".
216 Setting this allows an admin to define which entry in the tcpwrappers
217 config file will be used to control access to the daemon. This option
218 is only available when Exim is built with USE_TCP_WRAPPERS. The
219 default value is set at build time using the TCP_WRAPPERS_DAEMON_NAME
222 11. [POSSIBLE CONFIG BREAKAGE] The default value for system_filter_user is now
223 the Exim run-time user, instead of root.
225 12. [POSSIBLE CONFIG BREAKAGE] ALT_CONFIG_ROOT_ONLY is no longer optional and
226 is forced on. This is mitigated by the new build option
227 TRUSTED_CONFIG_LIST which defines a list of configuration files which
228 are trusted; one per line. If a config file is owned by root and matches
229 a pathname in the list, then it may be invoked by the Exim build-time
230 user without Exim relinquishing root privileges.
232 13. [POSSIBLE CONFIG BREAKAGE] The Exim user is no longer automatically
233 trusted to supply -D<Macro[=Value]> overrides on the command-line. Going
234 forward, we recommend using TRUSTED_CONFIG_LIST with shim configs that
235 include the main config. As a transition mechanism, we are temporarily
236 providing a work-around: the new build option WHITELIST_D_MACROS provides
237 a colon-separated list of macro names which may be overridden by the Exim
238 run-time user. The values of these macros are constrained to the regex
239 ^[A-Za-z0-9_/.-]*$ (which explicitly does allow for empty values).
245 1. TWO SECURITY FIXES: one relating to mail-spools which are globally
246 writable, the other to locking of MBX folders (not mbox).
248 2. MySQL stored procedures are now supported.
250 3. The dkim_domain transport option is now a list, not a single string, and
251 messages will be signed for each element in the list (discarding
254 4. The 4.70 release unexpectedly changed the behaviour of dnsdb TXT lookups
255 in the presence of multiple character strings within the RR. Prior to 4.70,
256 only the first string would be returned. The dnsdb lookup now, by default,
257 preserves the pre-4.70 semantics, but also now takes an extended output
258 separator specification. The separator can be followed by a semicolon, to
259 concatenate the individual text strings together with no join character,
260 or by a comma and a second separator character, in which case the text
261 strings within a TXT record are joined on that second character.
262 Administrators are reminded that DNS provides no ordering guarantees
263 between multiple records in an RRset. For example:
265 foo.example. IN TXT "a" "b" "c"
266 foo.example. IN TXT "d" "e" "f"
268 ${lookup dnsdb{>/ txt=foo.example}} -> "a/d"
269 ${lookup dnsdb{>/; txt=foo.example}} -> "def/abc"
270 ${lookup dnsdb{>/,+ txt=foo.example}} -> "a+b+c/d+e+f"
276 1. Native DKIM support without an external library.
277 (Note that if no action to prevent it is taken, a straight upgrade will
278 result in DKIM verification of all signed incoming emails. See spec
279 for details on conditionally disabling)
281 2. Experimental DCC support via dccifd (contributed by Wolfgang Breyha).
283 3. There is now a bool{} expansion condition which maps certain strings to
284 true/false condition values (most likely of use in conjunction with the
285 and{} expansion operator).
287 4. The $spam_score, $spam_bar and $spam_report variables are now available
290 5. exim -bP now supports "macros", "macro_list" or "macro MACRO_NAME" as
291 options, provided that Exim is invoked by an admin_user.
293 6. There is a new option gnutls_compat_mode, when linked against GnuTLS,
294 which increases compatibility with older clients at the cost of decreased
295 security. Don't set this unless you need to support such clients.
297 7. There is a new expansion operator, ${randint:...} which will produce a
298 "random" number less than the supplied integer. This randomness is
299 not guaranteed to be cryptographically strong, but depending upon how
300 Exim was built may be better than the most naive schemes.
302 8. Exim now explicitly ensures that SHA256 is available when linked against
305 9. The transport_filter_timeout option now applies to SMTP transports too.
311 1. Preliminary DKIM support in Experimental.
317 1. The body_linecount and body_zerocount C variables are now exported in the
320 2. When a dnslists lookup succeeds, the key that was looked up is now placed
321 in $dnslist_matched. When the key is an IP address, it is not reversed in
322 this variable (though it is, of course, in the actual lookup). In simple
325 deny dnslists = spamhaus.example
327 the key is also available in another variable (in this case,
328 $sender_host_address). In more complicated cases, however, this is not
329 true. For example, using a data lookup might generate a dnslists lookup
332 deny dnslists = spamhaus.example/<|192.168.1.2|192.168.6.7|...
334 If this condition succeeds, the value in $dnslist_matched might be
335 192.168.6.7 (for example).
337 3. Authenticators now have a client_condition option. When Exim is running as
338 a client, it skips an authenticator whose client_condition expansion yields
339 "0", "no", or "false". This can be used, for example, to skip plain text
340 authenticators when the connection is not encrypted by a setting such as:
342 client_condition = ${if !eq{$tls_cipher}{}}
344 Note that the 4.67 documentation states that $tls_cipher contains the
345 cipher used for incoming messages. In fact, during SMTP delivery, it
346 contains the cipher used for the delivery. The same is true for
349 4. There is now a -Mvc <message-id> option, which outputs a copy of the
350 message to the standard output, in RFC 2822 format. The option can be used
351 only by an admin user.
353 5. There is now a /noupdate option for the ratelimit ACL condition. It
354 computes the rate and checks the limit as normal, but it does not update
355 the saved data. This means that, in relevant ACLs, it is possible to lookup
356 the existence of a specified (or auto-generated) ratelimit key without
357 incrementing the ratelimit counter for that key.
359 In order for this to be useful, another ACL entry must set the rate
360 for the same key somewhere (otherwise it will always be zero).
365 # Read the rate; if it doesn't exist or is below the maximum
367 deny ratelimit = 100 / 5m / strict / noupdate
368 log_message = RATE: $sender_rate / $sender_rate_period \
369 (max $sender_rate_limit)
371 [... some other logic and tests...]
373 warn ratelimit = 100 / 5m / strict / per_cmd
374 log_message = RATE UPDATE: $sender_rate / $sender_rate_period \
375 (max $sender_rate_limit)
376 condition = ${if le{$sender_rate}{$sender_rate_limit}}
380 6. The variable $max_received_linelength contains the number of bytes in the
381 longest line that was received as part of the message, not counting the
382 line termination character(s).
384 7. Host lists can now include +ignore_defer and +include_defer, analagous to
385 +ignore_unknown and +include_unknown. These options should be used with
386 care, probably only in non-critical host lists such as whitelists.
388 8. There's a new option called queue_only_load_latch, which defaults true.
389 If set false when queue_only_load is greater than zero, Exim re-evaluates
390 the load for each incoming message in an SMTP session. Otherwise, once one
391 message is queued, the remainder are also.
393 9. There is a new ACL, specified by acl_smtp_notquit, which is run in most
394 cases when an SMTP session ends without sending QUIT. However, when Exim
395 itself is is bad trouble, such as being unable to write to its log files,
396 this ACL is not run, because it might try to do things (such as write to
397 log files) that make the situation even worse.
399 Like the QUIT ACL, this new ACL is provided to make it possible to gather
400 statistics. Whatever it returns (accept or deny) is immaterial. The "delay"
401 modifier is forbidden in this ACL.
403 When the NOTQUIT ACL is running, the variable $smtp_notquit_reason is set
404 to a string that indicates the reason for the termination of the SMTP
405 connection. The possible values are:
407 acl-drop Another ACL issued a "drop" command
408 bad-commands Too many unknown or non-mail commands
409 command-timeout Timeout while reading SMTP commands
410 connection-lost The SMTP connection has been lost
411 data-timeout Timeout while reading message data
412 local-scan-error The local_scan() function crashed
413 local-scan-timeout The local_scan() function timed out
414 signal-exit SIGTERM or SIGINT
415 synchronization-error SMTP synchronization error
416 tls-failed TLS failed to start
418 In most cases when an SMTP connection is closed without having received
419 QUIT, Exim sends an SMTP response message before actually closing the
420 connection. With the exception of acl-drop, the default message can be
421 overridden by the "message" modifier in the NOTQUIT ACL. In the case of a
422 "drop" verb in another ACL, it is the message from the other ACL that is
425 10. For MySQL and PostgreSQL lookups, it is now possible to specify a list of
426 servers with individual queries. This is done by starting the query with
427 "servers=x:y:z;", where each item in the list may take one of two forms:
429 (1) If it is just a host name, the appropriate global option (mysql_servers
430 or pgsql_servers) is searched for a host of the same name, and the
431 remaining parameters (database, user, password) are taken from there.
433 (2) If it contains any slashes, it is taken as a complete parameter set.
435 The list of servers is used in exactly the same was as the global list.
436 Once a connection to a server has happened and a query has been
437 successfully executed, processing of the lookup ceases.
439 This feature is intended for use in master/slave situations where updates
440 are occurring, and one wants to update a master rather than a slave. If the
441 masters are in the list for reading, you might have:
443 mysql_servers = slave1/db/name/pw:slave2/db/name/pw:master/db/name/pw
445 In an updating lookup, you could then write
447 ${lookup mysql{servers=master; UPDATE ...}
449 If, on the other hand, the master is not to be used for reading lookups:
451 pgsql_servers = slave1/db/name/pw:slave2/db/name/pw
453 you can still update the master by
455 ${lookup pgsql{servers=master/db/name/pw; UPDATE ...}
457 11. The message_body_newlines option (default FALSE, for backwards
458 compatibility) can be used to control whether newlines are present in
459 $message_body and $message_body_end. If it is FALSE, they are replaced by
466 1. There is a new log selector called smtp_no_mail, which is not included in
467 the default setting. When it is set, a line is written to the main log
468 whenever an accepted SMTP connection terminates without having issued a
471 2. When an item in a dnslists list is followed by = and & and a list of IP
472 addresses, the behaviour was not clear when the lookup returned more than
473 one IP address. This has been solved by the addition of == and =& for "all"
474 rather than the default "any" matching.
476 3. Up till now, the only control over which cipher suites GnuTLS uses has been
477 for the cipher algorithms. New options have been added to allow some of the
478 other parameters to be varied.
480 4. There is a new compile-time option called ENABLE_DISABLE_FSYNC. When it is
481 set, Exim compiles a runtime option called disable_fsync.
483 5. There is a new variable called $smtp_count_at_connection_start.
485 6. There's a new control called no_pipelining.
487 7. There are two new variables called $sending_ip_address and $sending_port.
488 These are set whenever an SMTP connection to another host has been set up.
490 8. The expansion of the helo_data option in the smtp transport now happens
491 after the connection to the server has been made.
493 9. There is a new expansion operator ${rfc2047d: that decodes strings that
494 are encoded as per RFC 2047.
496 10. There is a new log selector called "pid", which causes the current process
497 id to be added to every log line, in square brackets, immediately after the
500 11. Exim has been modified so that it flushes SMTP output before implementing
501 a delay in an ACL. It also flushes the output before performing a callout,
502 as this can take a substantial time. These behaviours can be disabled by
503 obeying control = no_delay_flush or control = no_callout_flush,
504 respectively, at some earlier stage of the connection.
506 12. There are two new expansion conditions that iterate over a list. They are
507 called forany and forall.
509 13. There's a new global option called dsn_from that can be used to vary the
510 contents of From: lines in bounces and other automatically generated
511 messages ("delivery status notifications" - hence the name of the option).
513 14. The smtp transport has a new option called hosts_avoid_pipelining.
515 15. By default, exigrep does case-insensitive matches. There is now a -I option
516 that makes it case-sensitive.
518 16. A number of new features ("addresses", "map", "filter", and "reduce") have
519 been added to string expansions to make it easier to process lists of
520 items, typically addresses.
522 17. There's a new ACL modifier called "continue". It does nothing of itself,
523 and processing of the ACL always continues with the next condition or
524 modifier. It is provided so that the side effects of expanding its argument
527 18. It is now possible to use newline and other control characters (those with
528 values less than 32, plus DEL) as separators in lists.
530 19. The exigrep utility now has a -v option, which inverts the matching
533 20. The host_find_failed option in the manualroute router can now be set to
540 No new features were added to 4.66.
546 No new features were added to 4.65.
552 1. ACL variables can now be given arbitrary names, as long as they start with
553 "acl_c" or "acl_m" (for connection variables and message variables), are at
554 least six characters long, with the sixth character being either a digit or
557 2. There is a new ACL modifier called log_reject_target. It makes it possible
558 to specify which logs are used for messages about ACL rejections.
560 3. There is a new authenticator called "dovecot". This is an interface to the
561 authentication facility of the Dovecot POP/IMAP server, which can support a
562 number of authentication methods.
564 4. The variable $message_headers_raw provides a concatenation of all the
565 messages's headers without any decoding. This is in contrast to
566 $message_headers, which does RFC2047 decoding on the header contents.
568 5. In a DNS black list, if two domain names, comma-separated, are given, the
569 second is used first to do an initial check, making use of any IP value
570 restrictions that are set. If there is a match, the first domain is used,
571 without any IP value restrictions, to get the TXT record.
573 6. All authenticators now have a server_condition option.
575 7. There is a new command-line option called -Mset. It is useful only in
576 conjunction with -be (that is, when testing string expansions). It must be
577 followed by a message id; Exim loads the given message from its spool
578 before doing the expansions.
580 8. Another similar new command-line option is called -bem. It operates like
581 -be except that it must be followed by the name of a file that contains a
584 9. When an address is delayed because of a 4xx response to a RCPT command, it
585 is now the combination of sender and recipient that is delayed in
586 subsequent queue runs until its retry time is reached.
588 10. Unary negation and the bitwise logical operators and, or, xor, not, and
589 shift, have been added to the eval: and eval10: expansion items.
591 11. The variables $interface_address and $interface_port have been renamed
592 as $received_ip_address and $received_port, to make it clear that they
593 relate to message reception rather than delivery. (The old names remain
594 available for compatibility.)
596 12. The "message" modifier can now be used on "accept" and "discard" acl verbs
597 to vary the message that is sent when an SMTP command is accepted.
603 1. There is a new Boolean option called filter_prepend_home for the redirect
606 2. There is a new acl, set by acl_not_smtp_start, which is run right at the
607 start of receiving a non-SMTP message, before any of the message has been
610 3. When an SMTP error message is specified in a "message" modifier in an ACL,
611 or in a :fail: or :defer: message in a redirect router, Exim now checks the
612 start of the message for an SMTP error code.
614 4. There is a new parameter for LDAP lookups called "referrals", which takes
615 one of the settings "follow" (the default) or "nofollow".
617 5. Version 20070721.2 of exipick now included, offering these new options:
619 After all other sorting options have bee processed, reverse order
620 before displaying messages (-R is synonym).
622 Randomize order of matching messages before displaying.
624 Instead of displaying the matching messages, display the sum
626 --sort <variable>[,<variable>...]
627 Before displaying matching messages, sort the messages according to
628 each messages value for each variable.
630 Negate the value for every test (returns inverse output from the
631 same criteria without --not).
637 1. The ${readsocket expansion item now supports Internet domain sockets as well
638 as Unix domain sockets. If the first argument begins "inet:", it must be of
639 the form "inet:host:port". The port is mandatory; it may be a number or the
640 name of a TCP port in /etc/services. The host may be a name, or it may be an
641 IP address. An ip address may optionally be enclosed in square brackets.
642 This is best for IPv6 addresses. For example:
644 ${readsocket{inet:[::1]:1234}{<request data>}...
646 Only a single host name may be given, but if looking it up yield more than
647 one IP address, they are each tried in turn until a connection is made. Once
648 a connection has been made, the behaviour is as for ${readsocket with a Unix
651 2. If a redirect router sets up file or pipe deliveries for more than one
652 incoming address, and the relevant transport has batch_max set greater than
653 one, a batch delivery now occurs.
655 3. The appendfile transport has a new option called maildirfolder_create_regex.
656 Its value is a regular expression. For a maildir delivery, this is matched
657 against the maildir directory; if it matches, Exim ensures that a
658 maildirfolder file is created alongside the new, cur, and tmp directories.
664 The documentation is up-to-date for the 4.61 release. Major new features since
665 the 4.60 release are:
667 . An option called disable_ipv6, to disable the use of IPv6 completely.
669 . An increase in the number of ACL variables to 20 of each type.
671 . A change to use $auth1, $auth2, and $auth3 in authenticators instead of $1,
672 $2, $3, (though those are still set) because the numeric variables get used
673 for other things in complicated expansions.
675 . The default for rfc1413_query_timeout has been changed from 30s to 5s.
677 . It is possible to use setclassresources() on some BSD OS to control the
678 resources used in pipe deliveries.
680 . A new ACL modifier called add_header, which can be used with any verb.
682 . More errors are detectable in retry rules.
684 There are a number of other additions too.
690 The documentation is up-to-date for the 4.60 release. Major new features since
691 the 4.50 release are:
693 . Support for SQLite.
695 . Support for IGNOREQUOTA in LMTP.
697 . Extensions to the "submission mode" features.
699 . Support for Client SMTP Authorization (CSA).
701 . Support for ratelimiting hosts and users.
703 . New expansion items to help with the BATV "prvs" scheme.
705 . A "match_ip" condition, that matches an IP address against a list.
707 There are many more minor changes.