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 Git before the documentation is updated. Once
7 the documentation is updated, this file is reduced to a short list.
12 1. PKG_CONFIG_PATH can now be set in Local/Makefile;
13 wildcards will be expanded, values are collapsed.
15 2. The ${readsocket } expansion now takes an option to not shutdown the
16 connection after sending the query string. The default remains to do so.
18 3. An smtp transport option "hosts_noproxy_tls" to control whether multiple
19 deliveries on a single TCP connection can maintain a TLS connection
20 open. By default disabled for all hosts, doing so saves the cost of
21 making new TLS sessions, at the cost of having to proxy the data via
22 another process. Logging is also affected.
24 4. A malware connection type for the FPSCAND protocol.
26 5. An option for recipient verify callouts to hold the connection open for
27 further recipients and for delivery.
29 6. The reproducible build $SOURCE_DATE_EPOCH environment variable is now
32 7. Optionally, an alternate format for spool data-files which matches the
33 wire format - meaning more efficient reception and transmission (at the
34 cost of difficulty with standard Unix tools). Only used for messages
35 received using the ESMTP CHUNKING option, and when a new main-section
36 option "spool_wireformat" (false by default) is set.
38 8. New main configuration option "commandline_checks_require_admin" to
39 restrict who can use various introspection options.
41 9. New option modifier "no_check" for quota and quota_filecount
48 1. Allow relative config file names for ".include"
50 2. A main-section config option "debug_store" to control the checks on
51 variable locations during store-reset. Normally false but can be enabled
52 when a memory corrution issue is suspected on a production system.
58 1. The new perl_taintmode option allows to run the embedded perl
59 interpreter in taint mode.
61 2. New log_selector: dnssec, adds a "DS" tag to acceptance and delivery lines.
63 3. Speculative debugging, via a "kill" option to the "control=debug" ACL
66 4. New expansion item ${sha3:<string>} / ${sha3_<N>:<string>}.
67 N can be 224, 256 (default), 384, 512.
68 With GnuTLS 3.5.0 or later, only.
70 5. Facility for named queues: A command-line argument can specify
71 the queue name for a queue operation, and an ACL modifier can set
72 the queue to be used for a message. A $queue_name variable gives
75 6. New expansion operators base32/base32d.
77 7. The CHUNKING ESMTP extension from RFC 3030. May give some slight
78 performance increase and network load decrease. Main config option
79 chunking_advertise_hosts, and smtp transport option hosts_try_chunking
82 8. LMDB lookup support, as Experimental. Patch supplied by Andrew Colin Kissa.
84 9. Expansion operator escape8bit, like escape but not touching newline etc..
86 10. Feature macros, generated from compile options. All start with "_HAVE_"
87 and go on with some roughly recognisable name. Driver macros, for
88 router, transport and authentication drivers; names starting with "_DRIVER_".
89 Option macros, for each configuration-file option; all start with "_OPT_".
90 Use the "-bP macros" command-line option to see what is present.
92 11. Integer values for options can take a "G" multiplier.
94 12. defer=pass option for the ACL control cutthrough_delivery, to reflect 4xx
95 returns from the target back to the initiator, rather than spooling the
98 13. New built-in constants available for tls_dhparam and default changed.
100 14. If built with EXPERIMENTAL_QUEUEFILE, a queuefile transport, for writing
101 out copies of the message spool files for use by 3rd-party scanners.
103 15. A new option on the smtp transport, hosts_try_fastopen. If the system
104 supports it (on Linux it must be enabled in the kernel by the sysadmin)
105 try to use RFC 7413 "TCP Fast Open". No data is sent on the SYN segment
106 but it permits a peer that also supports the facility to send its SMTP
107 banner immediately after the SYN,ACK segment rather then waiting for
108 another ACK - so saving up to one roundtrip time. Because it requires
109 previous communication with the peer (we save a cookie from it) this
110 will only become active on frequently-contacted destinations.
112 16. A new syslog_pid option to suppress PID duplication in syslog lines.
118 1. The ACL conditions regex and mime_regex now capture substrings
119 into numeric variables $regex1 to 9, like the "match" expansion condition.
121 2. New $callout_address variable records the address used for a spam=,
122 malware= or verify= callout.
124 3. Transports now take a "max_parallel" option, to limit concurrency.
126 4. Expansion operators ${ipv6norm:<string>} and ${ipv6denorm:<string>}.
127 The latter expands to a 8-element colon-sep set of hex digits including
128 leading zeroes. A trailing ipv4-style dotted-decimal set is converted
129 to hex. Pure ipv4 addresses are converted to IPv4-mapped IPv6.
130 The former operator strips leading zeroes and collapses the longest
131 set of 0-groups to a double-colon.
133 5. New "-bP config" support, to dump the effective configuration.
135 6. New $dkim_key_length variable.
137 7. New base64d and base64 expansion items (the existing str2b64 being a
138 synonym of the latter). Add support in base64 for certificates.
140 8. New main configuration option "bounce_return_linesize_limit" to
141 avoid oversize bodies in bounces. The default value matches RFC
144 9. New $initial_cwd expansion variable.
150 1. Support for using the system standard CA bundle.
152 2. New expansion items $config_file, $config_dir, containing the file
153 and directory name of the main configuration file. Also $exim_version.
155 3. New "malware=" support for Avast.
157 4. New "spam=" variant option for Rspamd.
159 5. Assorted options on malware= and spam= scanners.
161 6. A command-line option to write a comment into the logfile.
163 7. If built with EXPERIMENTAL_SOCKS feature enabled, the smtp transport can
164 be configured to make connections via socks5 proxies.
166 8. If built with EXPERIMENTAL_INTERNATIONAL, support is included for
167 the transmission of UTF-8 envelope addresses.
169 9. If built with EXPERIMENTAL_INTERNATIONAL, an expansion item for a commonly
170 used encoding of Maildir folder names.
172 10. A logging option for slow DNS lookups.
174 11. New ${env {<variable>}} expansion.
176 12. A non-SMTP authenticator using information from TLS client certificates.
178 13. Main option "tls_eccurve" for selecting an Elliptic Curve for TLS.
179 Patch originally by Wolfgang Breyha.
181 14. Main option "dns_trust_aa" for trusting your local nameserver at the
182 same level as DNSSEC.
188 1. If built with EXPERIMENTAL_DANE feature enabled, Exim will follow the
189 DANE SMTP draft to assess a secure chain of trust of the certificate
190 used to establish the TLS connection based on a TLSA record in the
191 domain of the sender.
193 2. The EXPERIMENTAL_TPDA feature has been renamed to EXPERIMENTAL_EVENT
194 and several new events have been created. The reason is because it has
195 been expanded beyond just firing events during the transport phase. Any
196 existing TPDA transport options will have to be rewritten to use a new
197 $event_name expansion variable in a condition. Refer to the
198 experimental-spec.txt for details and examples.
200 3. The EXPERIMENTAL_CERTNAMES features is an enhancement to verify that
201 server certs used for TLS match the result of the MX lookup. It does
202 not use the same mechanism as DANE.
212 1. If built with the EXPERIMENTAL_PROXY feature enabled, Exim can be
213 configured to expect an initial header from a proxy that will make the
214 actual external source IP:host be used in exim instead of the IP of the
215 proxy that is connecting to it.
217 2. New verify option header_names_ascii, which will check to make sure
218 there are no non-ASCII characters in header names. Exim itself handles
219 those non-ASCII characters, but downstream apps may not, so Exim can
220 detect and reject if those characters are present.
222 3. New expansion operator ${utf8clean:string} to replace malformed UTF8
223 codepoints with valid ones.
225 4. New malware type "sock". Talks over a Unix or TCP socket, sending one
226 command line and matching a regex against the return data for trigger
227 and a second regex to extract malware_name. The mail spoolfile name can
228 be included in the command line.
230 5. The smtp transport now supports options "tls_verify_hosts" and
231 "tls_try_verify_hosts". If either is set the certificate verification
232 is split from the encryption operation. The default remains that a failed
233 verification cancels the encryption.
235 6. New SERVERS override of default ldap server list. In the ACLs, an ldap
236 lookup can now set a list of servers to use that is different from the
239 7. New command-line option -C for exiqgrep to specify alternate exim.conf
240 file when searching the queue.
242 8. OCSP now supports GnuTLS also, if you have version 3.1.3 or later of that.
244 9. Support for DNSSEC on outbound connections.
246 10. New variables "tls_(in,out)_(our,peer)cert" and expansion item
247 "certextract" to extract fields from them. Hash operators md5 and sha1
248 work over them for generating fingerprints, and a new sha256 operator
251 11. PRDR is now supported dy default.
253 12. OCSP stapling is now supported by default.
255 13. If built with the EXPERIMENTAL_DSN feature enabled, Exim will output
256 Delivery Status Notification messages in MIME format, and negotiate
257 DSN features per RFC 3461.
263 1. New command-line option -bI:sieve will list all supported sieve extensions
264 of this Exim build on standard output, one per line.
265 ManageSieve (RFC 5804) providers managing scripts for use by Exim should
266 query this to establish the correct list to include in the protocol's
267 SIEVE capability line.
269 2. If the -n option is combined with the -bP option, then the name of an
270 emitted option is not output, only the value (if visible to you).
271 For instance, "exim -n -bP pid_file_path" should just emit a pathname
272 followed by a newline, and no other text.
274 3. When built with SUPPORT_TLS and USE_GNUTLS, the SMTP transport driver now
275 has a "tls_dh_min_bits" option, to set the minimum acceptable number of
276 bits in the Diffie-Hellman prime offered by a server (in DH ciphersuites)
277 acceptable for security. (Option accepted but ignored if using OpenSSL).
278 Defaults to 1024, the old value. May be lowered only to 512, or raised as
279 far as you like. Raising this may hinder TLS interoperability with other
280 sites and is not currently recommended. Lowering this will permit you to
281 establish a TLS session which is not as secure as you might like.
283 Unless you really know what you are doing, leave it alone.
285 4. If not built with DISABLE_DNSSEC, Exim now has the main option
286 dns_dnssec_ok; if set to 1 then Exim will initialise the resolver library
287 to send the DO flag to your recursive resolver. If you have a recursive
288 resolver, which can set the Authenticated Data (AD) flag in results, Exim
289 can now detect this. Exim does not perform validation itself, instead
290 relying upon a trusted path to the resolver.
292 Current status: work-in-progress; $sender_host_dnssec variable added.
294 5. DSCP support for outbound connections: on a transport using the smtp driver,
295 set "dscp = ef", for instance, to cause the connections to have the relevant
296 DSCP (IPv4 TOS or IPv6 TCLASS) value in the header.
298 Similarly for inbound connections, there is a new control modifier, dscp,
299 so "warn control = dscp/ef" in the connect ACL, or after authentication.
301 Supported values depend upon system libraries. "exim -bI:dscp" to list the
302 ones Exim knows of. You can also set a raw number 0..0x3F.
304 6. The -G command-line flag is no longer ignored; it is now equivalent to an
305 ACL setting "control = suppress_local_fixups". The -L command-line flag
306 is now accepted and forces use of syslog, with the provided tag as the
307 process name. A few other flags used by Sendmail are now accepted and
310 7. New cutthrough routing feature. Requested by a "control = cutthrough_delivery"
311 ACL modifier; works for single-recipient mails which are received on and
312 deliverable via SMTP. Using the connection made for a recipient verify,
313 if requested before the verify, or a new one made for the purpose while
314 the inbound connection is still active. The bulk of the mail item is copied
315 direct from the inbound socket to the outbound (as well as the spool file).
316 When the source notifies the end of data, the data acceptance by the destination
317 is negotiated before the acceptance is sent to the source. If the destination
318 does not accept the mail item, for example due to content-scanning, the item
319 is not accepted from the source and therefore there is no need to generate
320 a bounce mail. This is of benefit when providing a secondary-MX service.
321 The downside is that delays are under the control of the ultimate destination
324 The Received-by: header on items delivered by cutthrough is generated
325 early in reception rather than at the end; this will affect any timestamp
326 included. The log line showing delivery is recorded before that showing
327 reception; it uses a new ">>" tag instead of "=>".
329 To support the feature, verify-callout connections can now use ESMTP and TLS.
330 The usual smtp transport options are honoured, plus a (new, default everything)
331 hosts_verify_avoid_tls.
333 New variable families named tls_in_cipher, tls_out_cipher etc. are introduced
334 for specific access to the information for each connection. The old names
335 are present for now but deprecated.
337 Not yet supported: IGNOREQUOTA, SIZE, PIPELINING.
339 8. New expansion operators ${listnamed:name} to get the content of a named list
340 and ${listcount:string} to count the items in a list.
342 9. New global option "gnutls_allow_auto_pkcs11", defaults false. The GnuTLS
343 rewrite in 4.80 combines with GnuTLS 2.12.0 or later, to autoload PKCS11
344 modules. For some situations this is desirable, but we expect admin in
345 those situations to know they want the feature. More commonly, it means
346 that GUI user modules get loaded and are broken by the setuid Exim being
347 unable to access files specified in environment variables and passed
348 through, thus breakage. So we explicitly inhibit the PKCS11 initialisation
349 unless this new option is set.
351 Some older OS's with earlier versions of GnuTLS might not have pkcs11 ability,
352 so have also added a build option which can be used to build Exim with GnuTLS
353 but without trying to use any kind of PKCS11 support. Uncomment this in the
356 AVOID_GNUTLS_PKCS11=yes
358 10. The "acl = name" condition on an ACL now supports optional arguments.
359 New expansion item "${acl {name}{arg}...}" and expansion condition
360 "acl {{name}{arg}...}" are added. In all cases up to nine arguments
361 can be used, appearing in $acl_arg1 to $acl_arg9 for the called ACL.
362 Variable $acl_narg contains the number of arguments. If the ACL sets
363 a "message =" value this becomes the result of the expansion item,
364 or the value of $value for the expansion condition. If the ACL returns
365 accept the expansion condition is true; if reject, false. A defer
366 return results in a forced fail.
368 11. Routers and transports can now have multiple headers_add and headers_remove
369 option lines. The concatenated list is used.
371 12. New ACL modifier "remove_header" can remove headers before message gets
372 handled by routers/transports.
374 13. New dnsdb lookup pseudo-type "a+". A sequence of "a6" (if configured),
375 "aaaa" and "a" lookups is done and the full set of results returned.
377 14. New expansion variable $headers_added with content from ACL add_header
378 modifier (but not yet added to message).
380 15. New 8bitmime status logging option for received messages. Log field "M8S".
382 16. New authenticated_sender logging option, adding to log field "A".
384 17. New expansion variables $router_name and $transport_name. Useful
385 particularly for debug_print as -bt command-line option does not
386 require privilege whereas -d does.
388 18. If built with EXPERIMENTAL_PRDR, per-recipient data responses per a
389 proposed extension to SMTP from Eric Hall.
391 19. The pipe transport has gained the force_command option, to allow
392 decorating commands from user .forward pipe aliases with prefix
393 wrappers, for instance.
395 20. Callout connections can now AUTH; the same controls as normal delivery
398 21. Support for DMARC, using opendmarc libs, can be enabled. It adds new
399 options: dmarc_forensic_sender, dmarc_history_file, and dmarc_tld_file.
400 It adds new expansion variables $dmarc_ar_header, $dmarc_status,
401 $dmarc_status_text, and $dmarc_used_domain. It adds a new acl modifier
402 dmarc_status. It adds new control flags dmarc_disable_verify and
403 dmarc_enable_forensic.
405 22. Add expansion variable $authenticated_fail_id, which is the username
406 provided to the authentication method which failed. It is available
407 for use in subsequent ACL processing (typically quit or notquit ACLs).
409 23. New ACL modifier "udpsend" can construct a UDP packet to send to a given
412 24. New ${hexquote:..string..} expansion operator converts non-printable
413 characters in the string to \xNN form.
415 25. Experimental TPDA (Transport Post Delivery Action) function added.
416 Patch provided by Axel Rau.
418 26. Experimental Redis lookup added. Patch provided by Warren Baker.
424 1. New authenticator driver, "gsasl". Server-only (at present).
425 This is a SASL interface, licensed under GPL, which can be found at
426 http://www.gnu.org/software/gsasl/.
427 This system does not provide sources of data for authentication, so
428 careful use needs to be made of the conditions in Exim.
430 2. New authenticator driver, "heimdal_gssapi". Server-only.
431 A replacement for using cyrus_sasl with Heimdal, now that $KRB5_KTNAME
432 is no longer honoured for setuid programs by Heimdal. Use the
433 "server_keytab" option to point to the keytab.
435 3. The "pkg-config" system can now be used when building Exim to reference
436 cflags and library information for lookups and authenticators, rather
437 than having to update "CFLAGS", "AUTH_LIBS", "LOOKUP_INCLUDE" and
438 "LOOKUP_LIBS" directly. Similarly for handling the TLS library support
439 without adjusting "TLS_INCLUDE" and "TLS_LIBS".
441 In addition, setting PCRE_CONFIG=yes will query the pcre-config tool to
442 find the headers and libraries for PCRE.
444 4. New expansion variable $tls_bits.
446 5. New lookup type, "dbmjz". Key is an Exim list, the elements of which will
447 be joined together with ASCII NUL characters to construct the key to pass
448 into the DBM library. Can be used with gsasl to access sasldb2 files as
451 6. OpenSSL now supports TLS1.1 and TLS1.2 with OpenSSL 1.0.1.
453 Avoid release 1.0.1a if you can. Note that the default value of
454 "openssl_options" is no longer "+dont_insert_empty_fragments", as that
455 increased susceptibility to attack. This may still have interoperability
456 implications for very old clients (see version 4.31 change 37) but
457 administrators can choose to make the trade-off themselves and restore
458 compatibility at the cost of session security.
460 7. Use of the new expansion variable $tls_sni in the main configuration option
461 tls_certificate will cause Exim to re-expand the option, if the client
462 sends the TLS Server Name Indication extension, to permit choosing a
463 different certificate; tls_privatekey will also be re-expanded. You must
464 still set these options to expand to valid files when $tls_sni is not set.
466 The SMTP Transport has gained the option tls_sni, which will set a hostname
467 for outbound TLS sessions, and set $tls_sni too.
469 A new log_selector, +tls_sni, has been added, to log received SNI values
470 for Exim as a server.
472 8. The existing "accept_8bitmime" option now defaults to true. This means
473 that Exim is deliberately not strictly RFC compliant. We're following
474 Dan Bernstein's advice in http://cr.yp.to/smtp/8bitmime.html by default.
475 Those who disagree, or know that they are talking to mail servers that,
476 even today, are not 8-bit clean, need to turn off this option.
478 9. Exim can now be started with -bw (with an optional timeout, given as
479 -bw<timespec>). With this, stdin at startup is a socket that is
480 already listening for connections. This has a more modern name of
481 "socket activation", but forcing the activated socket to fd 0. We're
482 interested in adding more support for modern variants.
484 10. ${eval } now uses 64-bit values on supporting platforms. A new "G" suffix
485 for numbers indicates multiplication by 1024^3.
487 11. The GnuTLS support has been revamped; the three options gnutls_require_kx,
488 gnutls_require_mac & gnutls_require_protocols are no longer supported.
489 tls_require_ciphers is now parsed by gnutls_priority_init(3) as a priority
490 string, documentation for which is at:
491 http://www.gnutls.org/manual/html_node/Priority-Strings.html
493 SNI support has been added to Exim's GnuTLS integration too.
495 For sufficiently recent GnuTLS libraries, ${randint:..} will now use
496 gnutls_rnd(), asking for GNUTLS_RND_NONCE level randomness.
498 12. With OpenSSL, if built with EXPERIMENTAL_OCSP, a new option tls_ocsp_file
499 is now available. If the contents of the file are valid, then Exim will
500 send that back in response to a TLS status request; this is OCSP Stapling.
501 Exim will not maintain the contents of the file in any way: administrators
502 are responsible for ensuring that it is up-to-date.
504 See "experimental-spec.txt" for more details.
506 13. ${lookup dnsdb{ }} supports now SPF record types. They are handled
507 identically to TXT record lookups.
509 14. New expansion variable $tod_epoch_l for higher-precision time.
511 15. New global option tls_dh_max_bits, defaulting to current value of NSS
512 hard-coded limit of DH ephemeral bits, to fix interop problems caused by
513 GnuTLS 2.12 library recommending a bit count higher than NSS supports.
515 16. tls_dhparam now used by both OpenSSL and GnuTLS, can be path or identifier.
516 Option can now be a path or an identifier for a standard prime.
517 If unset, we use the DH prime from section 2.2 of RFC 5114, "ike23".
518 Set to "historic" to get the old GnuTLS behaviour of auto-generated DH
521 17. SSLv2 now disabled by default in OpenSSL. (Never supported by GnuTLS).
522 Use "openssl_options -no_sslv2" to re-enable support, if your OpenSSL
523 install was not built with OPENSSL_NO_SSL2 ("no-ssl2").
529 1. New options for the ratelimit ACL condition: /count= and /unique=.
530 The /noupdate option has been replaced by a /readonly option.
532 2. The SMTP transport's protocol option may now be set to "smtps", to
533 use SSL-on-connect outbound.
535 3. New variable $av_failed, set true if the AV scanner deferred; ie, when
536 there is a problem talking to the AV scanner, or the AV scanner running.
538 4. New expansion conditions, "inlist" and "inlisti", which take simple lists
539 and check if the search item is a member of the list. This does not
540 support named lists, but does subject the list part to string expansion.
542 5. Unless the new EXPAND_LISTMATCH_RHS build option is set when Exim was
543 built, Exim no longer performs string expansion on the second string of
544 the match_* expansion conditions: "match_address", "match_domain",
545 "match_ip" & "match_local_part". Named lists can still be used.
551 1. The global option "dns_use_edns0" may be set to coerce EDNS0 usage on
552 or off in the resolver library.
558 1. In addition to the existing LDAP and LDAP/SSL ("ldaps") support, there
559 is now LDAP/TLS support, given sufficiently modern OpenLDAP client
560 libraries. The following global options have been added in support of
561 this: ldap_ca_cert_dir, ldap_ca_cert_file, ldap_cert_file, ldap_cert_key,
562 ldap_cipher_suite, ldap_require_cert, ldap_start_tls.
564 2. The pipe transport now takes a boolean option, "freeze_signal", default
565 false. When true, if the external delivery command exits on a signal then
566 Exim will freeze the message in the queue, instead of generating a bounce.
568 3. Log filenames may now use %M as an escape, instead of %D (still available).
569 The %M pattern expands to yyyymm, providing month-level resolution.
571 4. The $message_linecount variable is now updated for the maildir_tag option,
572 in the same way as $message_size, to reflect the real number of lines,
573 including any header additions or removals from transport.
575 5. When contacting a pool of SpamAssassin servers configured in spamd_address,
576 Exim now selects entries randomly, to better scale in a cluster setup.
582 1. SECURITY FIX: privilege escalation flaw fixed. On Linux (and only Linux)
583 the flaw permitted the Exim run-time user to cause root to append to
584 arbitrary files of the attacker's choosing, with the content based
585 on content supplied by the attacker.
587 2. Exim now supports loading some lookup types at run-time, using your
588 platform's dlopen() functionality. This has limited platform support
589 and the intention is not to support every variant, it's limited to
590 dlopen(). This permits the main Exim binary to not be linked against
591 all the libraries needed for all the lookup types.
597 NOTE: this version is not guaranteed backwards-compatible, please read the
598 items below carefully
600 1. A new main configuration option, "openssl_options", is available if Exim
601 is built with SSL support provided by OpenSSL. The option allows
602 administrators to specify OpenSSL options to be used on connections;
603 typically this is to set bug compatibility features which the OpenSSL
604 developers have not enabled by default. There may be security
605 consequences for certain options, so these should not be changed
608 2. A new pipe transport option, "permit_coredumps", may help with problem
609 diagnosis in some scenarios. Note that Exim is typically installed as
610 a setuid binary, which on most OSes will inhibit coredumps by default,
611 so that safety mechanism would have to be overridden for this option to
612 be able to take effect.
614 3. ClamAV 0.95 is now required for ClamAV support in Exim, unless
615 Local/Makefile sets: WITH_OLD_CLAMAV_STREAM=yes
616 Note that this switches Exim to use a new API ("INSTREAM") and a future
617 release of ClamAV will remove support for the old API ("STREAM").
619 The av_scanner option, when set to "clamd", now takes an optional third
620 part, "local", which causes Exim to pass a filename to ClamAV instead of
621 the file content. This is the same behaviour as when clamd is pointed at
622 a Unix-domain socket. For example:
624 av_scanner = clamd:192.0.2.3 1234:local
626 ClamAV's ExtendedDetectionInfo response format is now handled.
628 4. There is now a -bmalware option, restricted to admin users. This option
629 takes one parameter, a filename, and scans that file with Exim's
630 malware-scanning framework. This is intended purely as a debugging aid
631 to ensure that Exim's scanning is working, not to replace other tools.
632 Note that the ACL framework is not invoked, so if av_scanner references
633 ACL variables without a fallback then this will fail.
635 5. There is a new expansion operator, "reverse_ip", which will reverse IP
636 addresses; IPv4 into dotted quad, IPv6 into dotted nibble. Examples:
638 ${reverse_ip:192.0.2.4}
640 ${reverse_ip:2001:0db8:c42:9:1:abcd:192.0.2.3}
641 -> 3.0.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2
643 6. There is a new ACL control called "debug", to enable debug logging.
644 This allows selective logging of certain incoming transactions within
645 production environments, with some care. It takes two options, "tag"
646 and "opts"; "tag" is included in the filename of the log and "opts"
647 is used as per the -d<options> command-line option. Examples, which
648 don't all make sense in all contexts:
651 control = debug/tag=.$sender_host_address
652 control = debug/opts=+expand+acl
653 control = debug/tag=.$message_exim_id/opts=+expand
655 7. It has always been implicit in the design and the documentation that
656 "the Exim user" is not root. src/EDITME said that using root was
657 "very strongly discouraged". This is not enough to keep people from
658 shooting themselves in the foot in days when many don't configure Exim
659 themselves but via package build managers. The security consequences of
660 running various bits of network code are severe if there should be bugs in
661 them. As such, the Exim user may no longer be root. If configured
662 statically, Exim will refuse to build. If configured as ref:user then Exim
663 will exit shortly after start-up. If you must shoot yourself in the foot,
664 then henceforth you will have to maintain your own local patches to strip
667 8. There is a new expansion condition, bool_lax{}. Where bool{} uses the ACL
668 condition logic to determine truth/failure and will fail to expand many
669 strings, bool_lax{} uses the router condition logic, where most strings
671 Note: bool{00} is false, bool_lax{00} is true.
673 9. Routers now support multiple "condition" tests.
675 10. There is now a runtime configuration option "tcp_wrappers_daemon_name".
676 Setting this allows an admin to define which entry in the tcpwrappers
677 config file will be used to control access to the daemon. This option
678 is only available when Exim is built with USE_TCP_WRAPPERS. The
679 default value is set at build time using the TCP_WRAPPERS_DAEMON_NAME
682 11. [POSSIBLE CONFIG BREAKAGE] The default value for system_filter_user is now
683 the Exim run-time user, instead of root.
685 12. [POSSIBLE CONFIG BREAKAGE] ALT_CONFIG_ROOT_ONLY is no longer optional and
686 is forced on. This is mitigated by the new build option
687 TRUSTED_CONFIG_LIST which defines a list of configuration files which
688 are trusted; one per line. If a config file is owned by root and matches
689 a pathname in the list, then it may be invoked by the Exim build-time
690 user without Exim relinquishing root privileges.
692 13. [POSSIBLE CONFIG BREAKAGE] The Exim user is no longer automatically
693 trusted to supply -D<Macro[=Value]> overrides on the command-line. Going
694 forward, we recommend using TRUSTED_CONFIG_LIST with shim configs that
695 include the main config. As a transition mechanism, we are temporarily
696 providing a work-around: the new build option WHITELIST_D_MACROS provides
697 a colon-separated list of macro names which may be overridden by the Exim
698 run-time user. The values of these macros are constrained to the regex
699 ^[A-Za-z0-9_/.-]*$ (which explicitly does allow for empty values).
705 1. TWO SECURITY FIXES: one relating to mail-spools which are globally
706 writable, the other to locking of MBX folders (not mbox).
708 2. MySQL stored procedures are now supported.
710 3. The dkim_domain transport option is now a list, not a single string, and
711 messages will be signed for each element in the list (discarding
714 4. The 4.70 release unexpectedly changed the behaviour of dnsdb TXT lookups
715 in the presence of multiple character strings within the RR. Prior to 4.70,
716 only the first string would be returned. The dnsdb lookup now, by default,
717 preserves the pre-4.70 semantics, but also now takes an extended output
718 separator specification. The separator can be followed by a semicolon, to
719 concatenate the individual text strings together with no join character,
720 or by a comma and a second separator character, in which case the text
721 strings within a TXT record are joined on that second character.
722 Administrators are reminded that DNS provides no ordering guarantees
723 between multiple records in an RRset. For example:
725 foo.example. IN TXT "a" "b" "c"
726 foo.example. IN TXT "d" "e" "f"
728 ${lookup dnsdb{>/ txt=foo.example}} -> "a/d"
729 ${lookup dnsdb{>/; txt=foo.example}} -> "def/abc"
730 ${lookup dnsdb{>/,+ txt=foo.example}} -> "a+b+c/d+e+f"
736 1. Native DKIM support without an external library.
737 (Note that if no action to prevent it is taken, a straight upgrade will
738 result in DKIM verification of all signed incoming emails. See spec
739 for details on conditionally disabling)
741 2. Experimental DCC support via dccifd (contributed by Wolfgang Breyha).
743 3. There is now a bool{} expansion condition which maps certain strings to
744 true/false condition values (most likely of use in conjunction with the
745 and{} expansion operator).
747 4. The $spam_score, $spam_bar and $spam_report variables are now available
750 5. exim -bP now supports "macros", "macro_list" or "macro MACRO_NAME" as
751 options, provided that Exim is invoked by an admin_user.
753 6. There is a new option gnutls_compat_mode, when linked against GnuTLS,
754 which increases compatibility with older clients at the cost of decreased
755 security. Don't set this unless you need to support such clients.
757 7. There is a new expansion operator, ${randint:...} which will produce a
758 "random" number less than the supplied integer. This randomness is
759 not guaranteed to be cryptographically strong, but depending upon how
760 Exim was built may be better than the most naive schemes.
762 8. Exim now explicitly ensures that SHA256 is available when linked against
765 9. The transport_filter_timeout option now applies to SMTP transports too.
771 1. Preliminary DKIM support in Experimental.
777 1. The body_linecount and body_zerocount C variables are now exported in the
780 2. When a dnslists lookup succeeds, the key that was looked up is now placed
781 in $dnslist_matched. When the key is an IP address, it is not reversed in
782 this variable (though it is, of course, in the actual lookup). In simple
785 deny dnslists = spamhaus.example
787 the key is also available in another variable (in this case,
788 $sender_host_address). In more complicated cases, however, this is not
789 true. For example, using a data lookup might generate a dnslists lookup
792 deny dnslists = spamhaus.example/<|192.168.1.2|192.168.6.7|...
794 If this condition succeeds, the value in $dnslist_matched might be
795 192.168.6.7 (for example).
797 3. Authenticators now have a client_condition option. When Exim is running as
798 a client, it skips an authenticator whose client_condition expansion yields
799 "0", "no", or "false". This can be used, for example, to skip plain text
800 authenticators when the connection is not encrypted by a setting such as:
802 client_condition = ${if !eq{$tls_cipher}{}}
804 Note that the 4.67 documentation states that $tls_cipher contains the
805 cipher used for incoming messages. In fact, during SMTP delivery, it
806 contains the cipher used for the delivery. The same is true for
809 4. There is now a -Mvc <message-id> option, which outputs a copy of the
810 message to the standard output, in RFC 2822 format. The option can be used
811 only by an admin user.
813 5. There is now a /noupdate option for the ratelimit ACL condition. It
814 computes the rate and checks the limit as normal, but it does not update
815 the saved data. This means that, in relevant ACLs, it is possible to lookup
816 the existence of a specified (or auto-generated) ratelimit key without
817 incrementing the ratelimit counter for that key.
819 In order for this to be useful, another ACL entry must set the rate
820 for the same key somewhere (otherwise it will always be zero).
825 # Read the rate; if it doesn't exist or is below the maximum
827 deny ratelimit = 100 / 5m / strict / noupdate
828 log_message = RATE: $sender_rate / $sender_rate_period \
829 (max $sender_rate_limit)
831 [... some other logic and tests...]
833 warn ratelimit = 100 / 5m / strict / per_cmd
834 log_message = RATE UPDATE: $sender_rate / $sender_rate_period \
835 (max $sender_rate_limit)
836 condition = ${if le{$sender_rate}{$sender_rate_limit}}
840 6. The variable $max_received_linelength contains the number of bytes in the
841 longest line that was received as part of the message, not counting the
842 line termination character(s).
844 7. Host lists can now include +ignore_defer and +include_defer, analagous to
845 +ignore_unknown and +include_unknown. These options should be used with
846 care, probably only in non-critical host lists such as whitelists.
848 8. There's a new option called queue_only_load_latch, which defaults true.
849 If set false when queue_only_load is greater than zero, Exim re-evaluates
850 the load for each incoming message in an SMTP session. Otherwise, once one
851 message is queued, the remainder are also.
853 9. There is a new ACL, specified by acl_smtp_notquit, which is run in most
854 cases when an SMTP session ends without sending QUIT. However, when Exim
855 itself is is bad trouble, such as being unable to write to its log files,
856 this ACL is not run, because it might try to do things (such as write to
857 log files) that make the situation even worse.
859 Like the QUIT ACL, this new ACL is provided to make it possible to gather
860 statistics. Whatever it returns (accept or deny) is immaterial. The "delay"
861 modifier is forbidden in this ACL.
863 When the NOTQUIT ACL is running, the variable $smtp_notquit_reason is set
864 to a string that indicates the reason for the termination of the SMTP
865 connection. The possible values are:
867 acl-drop Another ACL issued a "drop" command
868 bad-commands Too many unknown or non-mail commands
869 command-timeout Timeout while reading SMTP commands
870 connection-lost The SMTP connection has been lost
871 data-timeout Timeout while reading message data
872 local-scan-error The local_scan() function crashed
873 local-scan-timeout The local_scan() function timed out
874 signal-exit SIGTERM or SIGINT
875 synchronization-error SMTP synchronization error
876 tls-failed TLS failed to start
878 In most cases when an SMTP connection is closed without having received
879 QUIT, Exim sends an SMTP response message before actually closing the
880 connection. With the exception of acl-drop, the default message can be
881 overridden by the "message" modifier in the NOTQUIT ACL. In the case of a
882 "drop" verb in another ACL, it is the message from the other ACL that is
885 10. For MySQL and PostgreSQL lookups, it is now possible to specify a list of
886 servers with individual queries. This is done by starting the query with
887 "servers=x:y:z;", where each item in the list may take one of two forms:
889 (1) If it is just a host name, the appropriate global option (mysql_servers
890 or pgsql_servers) is searched for a host of the same name, and the
891 remaining parameters (database, user, password) are taken from there.
893 (2) If it contains any slashes, it is taken as a complete parameter set.
895 The list of servers is used in exactly the same was as the global list.
896 Once a connection to a server has happened and a query has been
897 successfully executed, processing of the lookup ceases.
899 This feature is intended for use in master/slave situations where updates
900 are occurring, and one wants to update a master rather than a slave. If the
901 masters are in the list for reading, you might have:
903 mysql_servers = slave1/db/name/pw:slave2/db/name/pw:master/db/name/pw
905 In an updating lookup, you could then write
907 ${lookup mysql{servers=master; UPDATE ...}
909 If, on the other hand, the master is not to be used for reading lookups:
911 pgsql_servers = slave1/db/name/pw:slave2/db/name/pw
913 you can still update the master by
915 ${lookup pgsql{servers=master/db/name/pw; UPDATE ...}
917 11. The message_body_newlines option (default FALSE, for backwards
918 compatibility) can be used to control whether newlines are present in
919 $message_body and $message_body_end. If it is FALSE, they are replaced by
926 1. There is a new log selector called smtp_no_mail, which is not included in
927 the default setting. When it is set, a line is written to the main log
928 whenever an accepted SMTP connection terminates without having issued a
931 2. When an item in a dnslists list is followed by = and & and a list of IP
932 addresses, the behaviour was not clear when the lookup returned more than
933 one IP address. This has been solved by the addition of == and =& for "all"
934 rather than the default "any" matching.
936 3. Up till now, the only control over which cipher suites GnuTLS uses has been
937 for the cipher algorithms. New options have been added to allow some of the
938 other parameters to be varied.
940 4. There is a new compile-time option called ENABLE_DISABLE_FSYNC. When it is
941 set, Exim compiles a runtime option called disable_fsync.
943 5. There is a new variable called $smtp_count_at_connection_start.
945 6. There's a new control called no_pipelining.
947 7. There are two new variables called $sending_ip_address and $sending_port.
948 These are set whenever an SMTP connection to another host has been set up.
950 8. The expansion of the helo_data option in the smtp transport now happens
951 after the connection to the server has been made.
953 9. There is a new expansion operator ${rfc2047d: that decodes strings that
954 are encoded as per RFC 2047.
956 10. There is a new log selector called "pid", which causes the current process
957 id to be added to every log line, in square brackets, immediately after the
960 11. Exim has been modified so that it flushes SMTP output before implementing
961 a delay in an ACL. It also flushes the output before performing a callout,
962 as this can take a substantial time. These behaviours can be disabled by
963 obeying control = no_delay_flush or control = no_callout_flush,
964 respectively, at some earlier stage of the connection.
966 12. There are two new expansion conditions that iterate over a list. They are
967 called forany and forall.
969 13. There's a new global option called dsn_from that can be used to vary the
970 contents of From: lines in bounces and other automatically generated
971 messages ("delivery status notifications" - hence the name of the option).
973 14. The smtp transport has a new option called hosts_avoid_pipelining.
975 15. By default, exigrep does case-insensitive matches. There is now a -I option
976 that makes it case-sensitive.
978 16. A number of new features ("addresses", "map", "filter", and "reduce") have
979 been added to string expansions to make it easier to process lists of
980 items, typically addresses.
982 17. There's a new ACL modifier called "continue". It does nothing of itself,
983 and processing of the ACL always continues with the next condition or
984 modifier. It is provided so that the side effects of expanding its argument
987 18. It is now possible to use newline and other control characters (those with
988 values less than 32, plus DEL) as separators in lists.
990 19. The exigrep utility now has a -v option, which inverts the matching
993 20. The host_find_failed option in the manualroute router can now be set to
1000 No new features were added to 4.66.
1006 No new features were added to 4.65.
1012 1. ACL variables can now be given arbitrary names, as long as they start with
1013 "acl_c" or "acl_m" (for connection variables and message variables), are at
1014 least six characters long, with the sixth character being either a digit or
1017 2. There is a new ACL modifier called log_reject_target. It makes it possible
1018 to specify which logs are used for messages about ACL rejections.
1020 3. There is a new authenticator called "dovecot". This is an interface to the
1021 authentication facility of the Dovecot POP/IMAP server, which can support a
1022 number of authentication methods.
1024 4. The variable $message_headers_raw provides a concatenation of all the
1025 messages's headers without any decoding. This is in contrast to
1026 $message_headers, which does RFC2047 decoding on the header contents.
1028 5. In a DNS black list, if two domain names, comma-separated, are given, the
1029 second is used first to do an initial check, making use of any IP value
1030 restrictions that are set. If there is a match, the first domain is used,
1031 without any IP value restrictions, to get the TXT record.
1033 6. All authenticators now have a server_condition option.
1035 7. There is a new command-line option called -Mset. It is useful only in
1036 conjunction with -be (that is, when testing string expansions). It must be
1037 followed by a message id; Exim loads the given message from its spool
1038 before doing the expansions.
1040 8. Another similar new command-line option is called -bem. It operates like
1041 -be except that it must be followed by the name of a file that contains a
1044 9. When an address is delayed because of a 4xx response to a RCPT command, it
1045 is now the combination of sender and recipient that is delayed in
1046 subsequent queue runs until its retry time is reached.
1048 10. Unary negation and the bitwise logical operators and, or, xor, not, and
1049 shift, have been added to the eval: and eval10: expansion items.
1051 11. The variables $interface_address and $interface_port have been renamed
1052 as $received_ip_address and $received_port, to make it clear that they
1053 relate to message reception rather than delivery. (The old names remain
1054 available for compatibility.)
1056 12. The "message" modifier can now be used on "accept" and "discard" acl verbs
1057 to vary the message that is sent when an SMTP command is accepted.
1063 1. There is a new Boolean option called filter_prepend_home for the redirect
1066 2. There is a new acl, set by acl_not_smtp_start, which is run right at the
1067 start of receiving a non-SMTP message, before any of the message has been
1070 3. When an SMTP error message is specified in a "message" modifier in an ACL,
1071 or in a :fail: or :defer: message in a redirect router, Exim now checks the
1072 start of the message for an SMTP error code.
1074 4. There is a new parameter for LDAP lookups called "referrals", which takes
1075 one of the settings "follow" (the default) or "nofollow".
1077 5. Version 20070721.2 of exipick now included, offering these new options:
1079 After all other sorting options have bee processed, reverse order
1080 before displaying messages (-R is synonym).
1082 Randomize order of matching messages before displaying.
1084 Instead of displaying the matching messages, display the sum
1086 --sort <variable>[,<variable>...]
1087 Before displaying matching messages, sort the messages according to
1088 each messages value for each variable.
1090 Negate the value for every test (returns inverse output from the
1091 same criteria without --not).
1097 1. The ${readsocket expansion item now supports Internet domain sockets as well
1098 as Unix domain sockets. If the first argument begins "inet:", it must be of
1099 the form "inet:host:port". The port is mandatory; it may be a number or the
1100 name of a TCP port in /etc/services. The host may be a name, or it may be an
1101 IP address. An ip address may optionally be enclosed in square brackets.
1102 This is best for IPv6 addresses. For example:
1104 ${readsocket{inet:[::1]:1234}{<request data>}...
1106 Only a single host name may be given, but if looking it up yield more than
1107 one IP address, they are each tried in turn until a connection is made. Once
1108 a connection has been made, the behaviour is as for ${readsocket with a Unix
1111 2. If a redirect router sets up file or pipe deliveries for more than one
1112 incoming address, and the relevant transport has batch_max set greater than
1113 one, a batch delivery now occurs.
1115 3. The appendfile transport has a new option called maildirfolder_create_regex.
1116 Its value is a regular expression. For a maildir delivery, this is matched
1117 against the maildir directory; if it matches, Exim ensures that a
1118 maildirfolder file is created alongside the new, cur, and tmp directories.
1124 The documentation is up-to-date for the 4.61 release. Major new features since
1125 the 4.60 release are:
1127 . An option called disable_ipv6, to disable the use of IPv6 completely.
1129 . An increase in the number of ACL variables to 20 of each type.
1131 . A change to use $auth1, $auth2, and $auth3 in authenticators instead of $1,
1132 $2, $3, (though those are still set) because the numeric variables get used
1133 for other things in complicated expansions.
1135 . The default for rfc1413_query_timeout has been changed from 30s to 5s.
1137 . It is possible to use setclassresources() on some BSD OS to control the
1138 resources used in pipe deliveries.
1140 . A new ACL modifier called add_header, which can be used with any verb.
1142 . More errors are detectable in retry rules.
1144 There are a number of other additions too.
1150 The documentation is up-to-date for the 4.60 release. Major new features since
1151 the 4.50 release are:
1153 . Support for SQLite.
1155 . Support for IGNOREQUOTA in LMTP.
1157 . Extensions to the "submission mode" features.
1159 . Support for Client SMTP Authorization (CSA).
1161 . Support for ratelimiting hosts and users.
1163 . New expansion items to help with the BATV "prvs" scheme.
1165 . A "match_ip" condition, that matches an IP address against a list.
1167 There are many more minor changes.
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