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. Dual-certificate stacks on servers now support OCSP stapling, under GnuTLS
13 version 3.5.6 or later.
15 2. DANE is now supported under GnuTLS version 3.0.0 or later. Both GnuTLS and
16 OpenSSL versions are moved to mainline support from Experimental.
17 New SMTP transport option "dane_require_tls_ciphers".
19 3. Feature macros for the compiled-in set of malware scanner interfaces.
21 4. SPF support is promoted from Experimental to mainline status. The template
22 src/EDITME makefile does not enable its inclusion.
24 5. Logging control for DKIM verification. The existing DKIM log line is
25 controlled by a "dkim_verbose" selector which is _not_ enabled by default.
26 A new tag "DKIM=<domain>" is added to <= lines by default, controlled by
27 a "dkim" log_selector.
29 6. Receive duration on <= lines, under a new log_selector "receive_time".
31 7. Options "ipv4_only" and "ipv4_prefer" on the dnslookup router and on
32 routing rules in the manualroute router.
34 8. Expansion item ${sha3:<string>} / ${sha3_<N>:<string>} now also supported
35 under OpenSSL version 1.1.1 or later.
37 9. DKIM operations can now use the Ed25519 algorithm in addition to RSA, under
38 GnuTLS 3.6.0 or OpenSSL 1.1.1 or later.
40 10. Builtin feature-macros _CRYPTO_HASH_SHA3 and _CRYPTO_SIGN_ED25519, library
43 11. "exim -bP macro <name>" returns caller-usable status.
45 12. Expansion item ${authresults {<machine>}} for creating an
46 Authentication-Results: header.
48 13. EXPERIMENTAL_ARC. See the experimental.spec file.
50 14: A dane:fail event, intended to facilitate reporting.
52 15. "Lightweight" support for Redis Cluster. Requires redis_servers list to
53 contain all the servers in the cluster, all of which must be reachable from
54 the running exim instance. If the cluster has master/slave replication, the
55 list must contain all the master and slave servers.
57 16. Add an option to the Avast scanner interface: "pass_unscanned". This
58 allows to treat unscanned files as clean. Files may be unscanned for
59 several reasons: decompression bombs, broken archives.
65 1. PKG_CONFIG_PATH can now be set in Local/Makefile;
66 wildcards will be expanded, values are collapsed.
68 2. The ${readsocket } expansion now takes an option to not shutdown the
69 connection after sending the query string. The default remains to do so.
71 3. An smtp transport option "hosts_noproxy_tls" to control whether multiple
72 deliveries on a single TCP connection can maintain a TLS connection
73 open. By default disabled for all hosts, doing so saves the cost of
74 making new TLS sessions, at the cost of having to proxy the data via
75 another process. Logging is also affected.
77 4. A malware connection type for the FPSCAND protocol.
79 5. An option for recipient verify callouts to hold the connection open for
80 further recipients and for delivery.
82 6. The reproducible build $SOURCE_DATE_EPOCH environment variable is now
85 7. Optionally, an alternate format for spool data-files which matches the
86 wire format - meaning more efficient reception and transmission (at the
87 cost of difficulty with standard Unix tools). Only used for messages
88 received using the ESMTP CHUNKING option, and when a new main-section
89 option "spool_wireformat" (false by default) is set.
91 8. New main configuration option "commandline_checks_require_admin" to
92 restrict who can use various introspection options.
94 9. New option modifier "no_check" for quota and quota_filecount
97 10. Variable $smtp_command_history returning a comma-sep list of recent
100 11. Millisecond timetamps in logs, on log_selector "millisec". Also affects
101 log elements QT, DT and D, and timstamps in debug output.
103 12. TCP Fast Open logging. As a server, logs when the SMTP banner was sent
104 while still in SYN_RECV state; as a client logs when the connection
105 is opened with a TFO cookie.
107 13. DKIM support for multiple signing, by domain and/or key-selector.
108 DKIM support for multiple hashes, and for alternate-identity tags.
109 Builtin macro with default list of signed headers.
110 Better syntax for specifying oversigning.
111 The DKIM ACL can override verification status, and status is visible in
114 14. Exipick understands -C|--config for an alternative Exim
117 15. TCP Fast Open used, with data-on-SYN, for client SMTP via SOCKS5 proxy,
118 for ${readsocket } expansions, and for ClamAV.
120 16. The "-be" expansion test mode now supports macros. Macros are expanded
121 in test lines, and new macros can be defined.
123 17. Support for server-side dual-certificate-stacks (eg. RSA + ECDSA).
129 1. Allow relative config file names for ".include"
131 2. A main-section config option "debug_store" to control the checks on
132 variable locations during store-reset. Normally false but can be enabled
133 when a memory corrution issue is suspected on a production system.
139 1. The new perl_taintmode option allows to run the embedded perl
140 interpreter in taint mode.
142 2. New log_selector: dnssec, adds a "DS" tag to acceptance and delivery lines.
144 3. Speculative debugging, via a "kill" option to the "control=debug" ACL
147 4. New expansion item ${sha3:<string>} / ${sha3_<N>:<string>}.
148 N can be 224, 256 (default), 384, 512.
149 With GnuTLS 3.5.0 or later, only.
151 5. Facility for named queues: A command-line argument can specify
152 the queue name for a queue operation, and an ACL modifier can set
153 the queue to be used for a message. A $queue_name variable gives
156 6. New expansion operators base32/base32d.
158 7. The CHUNKING ESMTP extension from RFC 3030. May give some slight
159 performance increase and network load decrease. Main config option
160 chunking_advertise_hosts, and smtp transport option hosts_try_chunking
163 8. LMDB lookup support, as Experimental. Patch supplied by Andrew Colin Kissa.
165 9. Expansion operator escape8bit, like escape but not touching newline etc..
167 10. Feature macros, generated from compile options. All start with "_HAVE_"
168 and go on with some roughly recognisable name. Driver macros, for
169 router, transport and authentication drivers; names starting with "_DRIVER_".
170 Option macros, for each configuration-file option; all start with "_OPT_".
171 Use the "-bP macros" command-line option to see what is present.
173 11. Integer values for options can take a "G" multiplier.
175 12. defer=pass option for the ACL control cutthrough_delivery, to reflect 4xx
176 returns from the target back to the initiator, rather than spooling the
179 13. New built-in constants available for tls_dhparam and default changed.
181 14. If built with EXPERIMENTAL_QUEUEFILE, a queuefile transport, for writing
182 out copies of the message spool files for use by 3rd-party scanners.
184 15. A new option on the smtp transport, hosts_try_fastopen. If the system
185 supports it (on Linux it must be enabled in the kernel by the sysadmin)
186 try to use RFC 7413 "TCP Fast Open". No data is sent on the SYN segment
187 but it permits a peer that also supports the facility to send its SMTP
188 banner immediately after the SYN,ACK segment rather then waiting for
189 another ACK - so saving up to one roundtrip time. Because it requires
190 previous communication with the peer (we save a cookie from it) this
191 will only become active on frequently-contacted destinations.
193 16. A new syslog_pid option to suppress PID duplication in syslog lines.
199 1. The ACL conditions regex and mime_regex now capture substrings
200 into numeric variables $regex1 to 9, like the "match" expansion condition.
202 2. New $callout_address variable records the address used for a spam=,
203 malware= or verify= callout.
205 3. Transports now take a "max_parallel" option, to limit concurrency.
207 4. Expansion operators ${ipv6norm:<string>} and ${ipv6denorm:<string>}.
208 The latter expands to a 8-element colon-sep set of hex digits including
209 leading zeroes. A trailing ipv4-style dotted-decimal set is converted
210 to hex. Pure ipv4 addresses are converted to IPv4-mapped IPv6.
211 The former operator strips leading zeroes and collapses the longest
212 set of 0-groups to a double-colon.
214 5. New "-bP config" support, to dump the effective configuration.
216 6. New $dkim_key_length variable.
218 7. New base64d and base64 expansion items (the existing str2b64 being a
219 synonym of the latter). Add support in base64 for certificates.
221 8. New main configuration option "bounce_return_linesize_limit" to
222 avoid oversize bodies in bounces. The default value matches RFC
225 9. New $initial_cwd expansion variable.
231 1. Support for using the system standard CA bundle.
233 2. New expansion items $config_file, $config_dir, containing the file
234 and directory name of the main configuration file. Also $exim_version.
236 3. New "malware=" support for Avast.
238 4. New "spam=" variant option for Rspamd.
240 5. Assorted options on malware= and spam= scanners.
242 6. A command-line option to write a comment into the logfile.
244 7. If built with EXPERIMENTAL_SOCKS feature enabled, the smtp transport can
245 be configured to make connections via socks5 proxies.
247 8. If built with EXPERIMENTAL_INTERNATIONAL, support is included for
248 the transmission of UTF-8 envelope addresses.
250 9. If built with EXPERIMENTAL_INTERNATIONAL, an expansion item for a commonly
251 used encoding of Maildir folder names.
253 10. A logging option for slow DNS lookups.
255 11. New ${env {<variable>}} expansion.
257 12. A non-SMTP authenticator using information from TLS client certificates.
259 13. Main option "tls_eccurve" for selecting an Elliptic Curve for TLS.
260 Patch originally by Wolfgang Breyha.
262 14. Main option "dns_trust_aa" for trusting your local nameserver at the
263 same level as DNSSEC.
269 1. If built with EXPERIMENTAL_DANE feature enabled, Exim will follow the
270 DANE SMTP draft to assess a secure chain of trust of the certificate
271 used to establish the TLS connection based on a TLSA record in the
272 domain of the sender.
274 2. The EXPERIMENTAL_TPDA feature has been renamed to EXPERIMENTAL_EVENT
275 and several new events have been created. The reason is because it has
276 been expanded beyond just firing events during the transport phase. Any
277 existing TPDA transport options will have to be rewritten to use a new
278 $event_name expansion variable in a condition. Refer to the
279 experimental-spec.txt for details and examples.
281 3. The EXPERIMENTAL_CERTNAMES features is an enhancement to verify that
282 server certs used for TLS match the result of the MX lookup. It does
283 not use the same mechanism as DANE.
293 1. If built with the EXPERIMENTAL_PROXY feature enabled, Exim can be
294 configured to expect an initial header from a proxy that will make the
295 actual external source IP:host be used in exim instead of the IP of the
296 proxy that is connecting to it.
298 2. New verify option header_names_ascii, which will check to make sure
299 there are no non-ASCII characters in header names. Exim itself handles
300 those non-ASCII characters, but downstream apps may not, so Exim can
301 detect and reject if those characters are present.
303 3. New expansion operator ${utf8clean:string} to replace malformed UTF8
304 codepoints with valid ones.
306 4. New malware type "sock". Talks over a Unix or TCP socket, sending one
307 command line and matching a regex against the return data for trigger
308 and a second regex to extract malware_name. The mail spoolfile name can
309 be included in the command line.
311 5. The smtp transport now supports options "tls_verify_hosts" and
312 "tls_try_verify_hosts". If either is set the certificate verification
313 is split from the encryption operation. The default remains that a failed
314 verification cancels the encryption.
316 6. New SERVERS override of default ldap server list. In the ACLs, an ldap
317 lookup can now set a list of servers to use that is different from the
320 7. New command-line option -C for exiqgrep to specify alternate exim.conf
321 file when searching the queue.
323 8. OCSP now supports GnuTLS also, if you have version 3.1.3 or later of that.
325 9. Support for DNSSEC on outbound connections.
327 10. New variables "tls_(in,out)_(our,peer)cert" and expansion item
328 "certextract" to extract fields from them. Hash operators md5 and sha1
329 work over them for generating fingerprints, and a new sha256 operator
332 11. PRDR is now supported dy default.
334 12. OCSP stapling is now supported by default.
336 13. If built with the EXPERIMENTAL_DSN feature enabled, Exim will output
337 Delivery Status Notification messages in MIME format, and negotiate
338 DSN features per RFC 3461.
344 1. New command-line option -bI:sieve will list all supported sieve extensions
345 of this Exim build on standard output, one per line.
346 ManageSieve (RFC 5804) providers managing scripts for use by Exim should
347 query this to establish the correct list to include in the protocol's
348 SIEVE capability line.
350 2. If the -n option is combined with the -bP option, then the name of an
351 emitted option is not output, only the value (if visible to you).
352 For instance, "exim -n -bP pid_file_path" should just emit a pathname
353 followed by a newline, and no other text.
355 3. When built with SUPPORT_TLS and USE_GNUTLS, the SMTP transport driver now
356 has a "tls_dh_min_bits" option, to set the minimum acceptable number of
357 bits in the Diffie-Hellman prime offered by a server (in DH ciphersuites)
358 acceptable for security. (Option accepted but ignored if using OpenSSL).
359 Defaults to 1024, the old value. May be lowered only to 512, or raised as
360 far as you like. Raising this may hinder TLS interoperability with other
361 sites and is not currently recommended. Lowering this will permit you to
362 establish a TLS session which is not as secure as you might like.
364 Unless you really know what you are doing, leave it alone.
366 4. If not built with DISABLE_DNSSEC, Exim now has the main option
367 dns_dnssec_ok; if set to 1 then Exim will initialise the resolver library
368 to send the DO flag to your recursive resolver. If you have a recursive
369 resolver, which can set the Authenticated Data (AD) flag in results, Exim
370 can now detect this. Exim does not perform validation itself, instead
371 relying upon a trusted path to the resolver.
373 Current status: work-in-progress; $sender_host_dnssec variable added.
375 5. DSCP support for outbound connections: on a transport using the smtp driver,
376 set "dscp = ef", for instance, to cause the connections to have the relevant
377 DSCP (IPv4 TOS or IPv6 TCLASS) value in the header.
379 Similarly for inbound connections, there is a new control modifier, dscp,
380 so "warn control = dscp/ef" in the connect ACL, or after authentication.
382 Supported values depend upon system libraries. "exim -bI:dscp" to list the
383 ones Exim knows of. You can also set a raw number 0..0x3F.
385 6. The -G command-line flag is no longer ignored; it is now equivalent to an
386 ACL setting "control = suppress_local_fixups". The -L command-line flag
387 is now accepted and forces use of syslog, with the provided tag as the
388 process name. A few other flags used by Sendmail are now accepted and
391 7. New cutthrough routing feature. Requested by a "control = cutthrough_delivery"
392 ACL modifier; works for single-recipient mails which are received on and
393 deliverable via SMTP. Using the connection made for a recipient verify,
394 if requested before the verify, or a new one made for the purpose while
395 the inbound connection is still active. The bulk of the mail item is copied
396 direct from the inbound socket to the outbound (as well as the spool file).
397 When the source notifies the end of data, the data acceptance by the destination
398 is negotiated before the acceptance is sent to the source. If the destination
399 does not accept the mail item, for example due to content-scanning, the item
400 is not accepted from the source and therefore there is no need to generate
401 a bounce mail. This is of benefit when providing a secondary-MX service.
402 The downside is that delays are under the control of the ultimate destination
405 The Received-by: header on items delivered by cutthrough is generated
406 early in reception rather than at the end; this will affect any timestamp
407 included. The log line showing delivery is recorded before that showing
408 reception; it uses a new ">>" tag instead of "=>".
410 To support the feature, verify-callout connections can now use ESMTP and TLS.
411 The usual smtp transport options are honoured, plus a (new, default everything)
412 hosts_verify_avoid_tls.
414 New variable families named tls_in_cipher, tls_out_cipher etc. are introduced
415 for specific access to the information for each connection. The old names
416 are present for now but deprecated.
418 Not yet supported: IGNOREQUOTA, SIZE, PIPELINING.
420 8. New expansion operators ${listnamed:name} to get the content of a named list
421 and ${listcount:string} to count the items in a list.
423 9. New global option "gnutls_allow_auto_pkcs11", defaults false. The GnuTLS
424 rewrite in 4.80 combines with GnuTLS 2.12.0 or later, to autoload PKCS11
425 modules. For some situations this is desirable, but we expect admin in
426 those situations to know they want the feature. More commonly, it means
427 that GUI user modules get loaded and are broken by the setuid Exim being
428 unable to access files specified in environment variables and passed
429 through, thus breakage. So we explicitly inhibit the PKCS11 initialisation
430 unless this new option is set.
432 Some older OS's with earlier versions of GnuTLS might not have pkcs11 ability,
433 so have also added a build option which can be used to build Exim with GnuTLS
434 but without trying to use any kind of PKCS11 support. Uncomment this in the
437 AVOID_GNUTLS_PKCS11=yes
439 10. The "acl = name" condition on an ACL now supports optional arguments.
440 New expansion item "${acl {name}{arg}...}" and expansion condition
441 "acl {{name}{arg}...}" are added. In all cases up to nine arguments
442 can be used, appearing in $acl_arg1 to $acl_arg9 for the called ACL.
443 Variable $acl_narg contains the number of arguments. If the ACL sets
444 a "message =" value this becomes the result of the expansion item,
445 or the value of $value for the expansion condition. If the ACL returns
446 accept the expansion condition is true; if reject, false. A defer
447 return results in a forced fail.
449 11. Routers and transports can now have multiple headers_add and headers_remove
450 option lines. The concatenated list is used.
452 12. New ACL modifier "remove_header" can remove headers before message gets
453 handled by routers/transports.
455 13. New dnsdb lookup pseudo-type "a+". A sequence of "a6" (if configured),
456 "aaaa" and "a" lookups is done and the full set of results returned.
458 14. New expansion variable $headers_added with content from ACL add_header
459 modifier (but not yet added to message).
461 15. New 8bitmime status logging option for received messages. Log field "M8S".
463 16. New authenticated_sender logging option, adding to log field "A".
465 17. New expansion variables $router_name and $transport_name. Useful
466 particularly for debug_print as -bt command-line option does not
467 require privilege whereas -d does.
469 18. If built with EXPERIMENTAL_PRDR, per-recipient data responses per a
470 proposed extension to SMTP from Eric Hall.
472 19. The pipe transport has gained the force_command option, to allow
473 decorating commands from user .forward pipe aliases with prefix
474 wrappers, for instance.
476 20. Callout connections can now AUTH; the same controls as normal delivery
479 21. Support for DMARC, using opendmarc libs, can be enabled. It adds new
480 options: dmarc_forensic_sender, dmarc_history_file, and dmarc_tld_file.
481 It adds new expansion variables $dmarc_ar_header, $dmarc_status,
482 $dmarc_status_text, and $dmarc_used_domain. It adds a new acl modifier
483 dmarc_status. It adds new control flags dmarc_disable_verify and
484 dmarc_enable_forensic. The default for the dmarc_tld_file option is
485 "/etc/exim/opendmarc.tlds" and can be changed via EDITME.
487 22. Add expansion variable $authenticated_fail_id, which is the username
488 provided to the authentication method which failed. It is available
489 for use in subsequent ACL processing (typically quit or notquit ACLs).
491 23. New ACL modifier "udpsend" can construct a UDP packet to send to a given
494 24. New ${hexquote:..string..} expansion operator converts non-printable
495 characters in the string to \xNN form.
497 25. Experimental TPDA (Transport Post Delivery Action) function added.
498 Patch provided by Axel Rau.
500 26. Experimental Redis lookup added. Patch provided by Warren Baker.
506 1. New authenticator driver, "gsasl". Server-only (at present).
507 This is a SASL interface, licensed under GPL, which can be found at
508 http://www.gnu.org/software/gsasl/.
509 This system does not provide sources of data for authentication, so
510 careful use needs to be made of the conditions in Exim.
512 2. New authenticator driver, "heimdal_gssapi". Server-only.
513 A replacement for using cyrus_sasl with Heimdal, now that $KRB5_KTNAME
514 is no longer honoured for setuid programs by Heimdal. Use the
515 "server_keytab" option to point to the keytab.
517 3. The "pkg-config" system can now be used when building Exim to reference
518 cflags and library information for lookups and authenticators, rather
519 than having to update "CFLAGS", "AUTH_LIBS", "LOOKUP_INCLUDE" and
520 "LOOKUP_LIBS" directly. Similarly for handling the TLS library support
521 without adjusting "TLS_INCLUDE" and "TLS_LIBS".
523 In addition, setting PCRE_CONFIG=yes will query the pcre-config tool to
524 find the headers and libraries for PCRE.
526 4. New expansion variable $tls_bits.
528 5. New lookup type, "dbmjz". Key is an Exim list, the elements of which will
529 be joined together with ASCII NUL characters to construct the key to pass
530 into the DBM library. Can be used with gsasl to access sasldb2 files as
533 6. OpenSSL now supports TLS1.1 and TLS1.2 with OpenSSL 1.0.1.
535 Avoid release 1.0.1a if you can. Note that the default value of
536 "openssl_options" is no longer "+dont_insert_empty_fragments", as that
537 increased susceptibility to attack. This may still have interoperability
538 implications for very old clients (see version 4.31 change 37) but
539 administrators can choose to make the trade-off themselves and restore
540 compatibility at the cost of session security.
542 7. Use of the new expansion variable $tls_sni in the main configuration option
543 tls_certificate will cause Exim to re-expand the option, if the client
544 sends the TLS Server Name Indication extension, to permit choosing a
545 different certificate; tls_privatekey will also be re-expanded. You must
546 still set these options to expand to valid files when $tls_sni is not set.
548 The SMTP Transport has gained the option tls_sni, which will set a hostname
549 for outbound TLS sessions, and set $tls_sni too.
551 A new log_selector, +tls_sni, has been added, to log received SNI values
552 for Exim as a server.
554 8. The existing "accept_8bitmime" option now defaults to true. This means
555 that Exim is deliberately not strictly RFC compliant. We're following
556 Dan Bernstein's advice in http://cr.yp.to/smtp/8bitmime.html by default.
557 Those who disagree, or know that they are talking to mail servers that,
558 even today, are not 8-bit clean, need to turn off this option.
560 9. Exim can now be started with -bw (with an optional timeout, given as
561 -bw<timespec>). With this, stdin at startup is a socket that is
562 already listening for connections. This has a more modern name of
563 "socket activation", but forcing the activated socket to fd 0. We're
564 interested in adding more support for modern variants.
566 10. ${eval } now uses 64-bit values on supporting platforms. A new "G" suffix
567 for numbers indicates multiplication by 1024^3.
569 11. The GnuTLS support has been revamped; the three options gnutls_require_kx,
570 gnutls_require_mac & gnutls_require_protocols are no longer supported.
571 tls_require_ciphers is now parsed by gnutls_priority_init(3) as a priority
572 string, documentation for which is at:
573 http://www.gnutls.org/manual/html_node/Priority-Strings.html
575 SNI support has been added to Exim's GnuTLS integration too.
577 For sufficiently recent GnuTLS libraries, ${randint:..} will now use
578 gnutls_rnd(), asking for GNUTLS_RND_NONCE level randomness.
580 12. With OpenSSL, if built with EXPERIMENTAL_OCSP, a new option tls_ocsp_file
581 is now available. If the contents of the file are valid, then Exim will
582 send that back in response to a TLS status request; this is OCSP Stapling.
583 Exim will not maintain the contents of the file in any way: administrators
584 are responsible for ensuring that it is up-to-date.
586 See "experimental-spec.txt" for more details.
588 13. ${lookup dnsdb{ }} supports now SPF record types. They are handled
589 identically to TXT record lookups.
591 14. New expansion variable $tod_epoch_l for higher-precision time.
593 15. New global option tls_dh_max_bits, defaulting to current value of NSS
594 hard-coded limit of DH ephemeral bits, to fix interop problems caused by
595 GnuTLS 2.12 library recommending a bit count higher than NSS supports.
597 16. tls_dhparam now used by both OpenSSL and GnuTLS, can be path or identifier.
598 Option can now be a path or an identifier for a standard prime.
599 If unset, we use the DH prime from section 2.2 of RFC 5114, "ike23".
600 Set to "historic" to get the old GnuTLS behaviour of auto-generated DH
603 17. SSLv2 now disabled by default in OpenSSL. (Never supported by GnuTLS).
604 Use "openssl_options -no_sslv2" to re-enable support, if your OpenSSL
605 install was not built with OPENSSL_NO_SSL2 ("no-ssl2").
611 1. New options for the ratelimit ACL condition: /count= and /unique=.
612 The /noupdate option has been replaced by a /readonly option.
614 2. The SMTP transport's protocol option may now be set to "smtps", to
615 use SSL-on-connect outbound.
617 3. New variable $av_failed, set true if the AV scanner deferred; ie, when
618 there is a problem talking to the AV scanner, or the AV scanner running.
620 4. New expansion conditions, "inlist" and "inlisti", which take simple lists
621 and check if the search item is a member of the list. This does not
622 support named lists, but does subject the list part to string expansion.
624 5. Unless the new EXPAND_LISTMATCH_RHS build option is set when Exim was
625 built, Exim no longer performs string expansion on the second string of
626 the match_* expansion conditions: "match_address", "match_domain",
627 "match_ip" & "match_local_part". Named lists can still be used.
633 1. The global option "dns_use_edns0" may be set to coerce EDNS0 usage on
634 or off in the resolver library.
640 1. In addition to the existing LDAP and LDAP/SSL ("ldaps") support, there
641 is now LDAP/TLS support, given sufficiently modern OpenLDAP client
642 libraries. The following global options have been added in support of
643 this: ldap_ca_cert_dir, ldap_ca_cert_file, ldap_cert_file, ldap_cert_key,
644 ldap_cipher_suite, ldap_require_cert, ldap_start_tls.
646 2. The pipe transport now takes a boolean option, "freeze_signal", default
647 false. When true, if the external delivery command exits on a signal then
648 Exim will freeze the message in the queue, instead of generating a bounce.
650 3. Log filenames may now use %M as an escape, instead of %D (still available).
651 The %M pattern expands to yyyymm, providing month-level resolution.
653 4. The $message_linecount variable is now updated for the maildir_tag option,
654 in the same way as $message_size, to reflect the real number of lines,
655 including any header additions or removals from transport.
657 5. When contacting a pool of SpamAssassin servers configured in spamd_address,
658 Exim now selects entries randomly, to better scale in a cluster setup.
664 1. SECURITY FIX: privilege escalation flaw fixed. On Linux (and only Linux)
665 the flaw permitted the Exim run-time user to cause root to append to
666 arbitrary files of the attacker's choosing, with the content based
667 on content supplied by the attacker.
669 2. Exim now supports loading some lookup types at run-time, using your
670 platform's dlopen() functionality. This has limited platform support
671 and the intention is not to support every variant, it's limited to
672 dlopen(). This permits the main Exim binary to not be linked against
673 all the libraries needed for all the lookup types.
679 NOTE: this version is not guaranteed backwards-compatible, please read the
680 items below carefully
682 1. A new main configuration option, "openssl_options", is available if Exim
683 is built with SSL support provided by OpenSSL. The option allows
684 administrators to specify OpenSSL options to be used on connections;
685 typically this is to set bug compatibility features which the OpenSSL
686 developers have not enabled by default. There may be security
687 consequences for certain options, so these should not be changed
690 2. A new pipe transport option, "permit_coredumps", may help with problem
691 diagnosis in some scenarios. Note that Exim is typically installed as
692 a setuid binary, which on most OSes will inhibit coredumps by default,
693 so that safety mechanism would have to be overridden for this option to
694 be able to take effect.
696 3. ClamAV 0.95 is now required for ClamAV support in Exim, unless
697 Local/Makefile sets: WITH_OLD_CLAMAV_STREAM=yes
698 Note that this switches Exim to use a new API ("INSTREAM") and a future
699 release of ClamAV will remove support for the old API ("STREAM").
701 The av_scanner option, when set to "clamd", now takes an optional third
702 part, "local", which causes Exim to pass a filename to ClamAV instead of
703 the file content. This is the same behaviour as when clamd is pointed at
704 a Unix-domain socket. For example:
706 av_scanner = clamd:192.0.2.3 1234:local
708 ClamAV's ExtendedDetectionInfo response format is now handled.
710 4. There is now a -bmalware option, restricted to admin users. This option
711 takes one parameter, a filename, and scans that file with Exim's
712 malware-scanning framework. This is intended purely as a debugging aid
713 to ensure that Exim's scanning is working, not to replace other tools.
714 Note that the ACL framework is not invoked, so if av_scanner references
715 ACL variables without a fallback then this will fail.
717 5. There is a new expansion operator, "reverse_ip", which will reverse IP
718 addresses; IPv4 into dotted quad, IPv6 into dotted nibble. Examples:
720 ${reverse_ip:192.0.2.4}
722 ${reverse_ip:2001:0db8:c42:9:1:abcd:192.0.2.3}
723 -> 3.0.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2
725 6. There is a new ACL control called "debug", to enable debug logging.
726 This allows selective logging of certain incoming transactions within
727 production environments, with some care. It takes two options, "tag"
728 and "opts"; "tag" is included in the filename of the log and "opts"
729 is used as per the -d<options> command-line option. Examples, which
730 don't all make sense in all contexts:
733 control = debug/tag=.$sender_host_address
734 control = debug/opts=+expand+acl
735 control = debug/tag=.$message_exim_id/opts=+expand
737 7. It has always been implicit in the design and the documentation that
738 "the Exim user" is not root. src/EDITME said that using root was
739 "very strongly discouraged". This is not enough to keep people from
740 shooting themselves in the foot in days when many don't configure Exim
741 themselves but via package build managers. The security consequences of
742 running various bits of network code are severe if there should be bugs in
743 them. As such, the Exim user may no longer be root. If configured
744 statically, Exim will refuse to build. If configured as ref:user then Exim
745 will exit shortly after start-up. If you must shoot yourself in the foot,
746 then henceforth you will have to maintain your own local patches to strip
749 8. There is a new expansion condition, bool_lax{}. Where bool{} uses the ACL
750 condition logic to determine truth/failure and will fail to expand many
751 strings, bool_lax{} uses the router condition logic, where most strings
753 Note: bool{00} is false, bool_lax{00} is true.
755 9. Routers now support multiple "condition" tests.
757 10. There is now a runtime configuration option "tcp_wrappers_daemon_name".
758 Setting this allows an admin to define which entry in the tcpwrappers
759 config file will be used to control access to the daemon. This option
760 is only available when Exim is built with USE_TCP_WRAPPERS. The
761 default value is set at build time using the TCP_WRAPPERS_DAEMON_NAME
764 11. [POSSIBLE CONFIG BREAKAGE] The default value for system_filter_user is now
765 the Exim run-time user, instead of root.
767 12. [POSSIBLE CONFIG BREAKAGE] ALT_CONFIG_ROOT_ONLY is no longer optional and
768 is forced on. This is mitigated by the new build option
769 TRUSTED_CONFIG_LIST which defines a list of configuration files which
770 are trusted; one per line. If a config file is owned by root and matches
771 a pathname in the list, then it may be invoked by the Exim build-time
772 user without Exim relinquishing root privileges.
774 13. [POSSIBLE CONFIG BREAKAGE] The Exim user is no longer automatically
775 trusted to supply -D<Macro[=Value]> overrides on the command-line. Going
776 forward, we recommend using TRUSTED_CONFIG_LIST with shim configs that
777 include the main config. As a transition mechanism, we are temporarily
778 providing a work-around: the new build option WHITELIST_D_MACROS provides
779 a colon-separated list of macro names which may be overridden by the Exim
780 run-time user. The values of these macros are constrained to the regex
781 ^[A-Za-z0-9_/.-]*$ (which explicitly does allow for empty values).
787 1. TWO SECURITY FIXES: one relating to mail-spools which are globally
788 writable, the other to locking of MBX folders (not mbox).
790 2. MySQL stored procedures are now supported.
792 3. The dkim_domain transport option is now a list, not a single string, and
793 messages will be signed for each element in the list (discarding
796 4. The 4.70 release unexpectedly changed the behaviour of dnsdb TXT lookups
797 in the presence of multiple character strings within the RR. Prior to 4.70,
798 only the first string would be returned. The dnsdb lookup now, by default,
799 preserves the pre-4.70 semantics, but also now takes an extended output
800 separator specification. The separator can be followed by a semicolon, to
801 concatenate the individual text strings together with no join character,
802 or by a comma and a second separator character, in which case the text
803 strings within a TXT record are joined on that second character.
804 Administrators are reminded that DNS provides no ordering guarantees
805 between multiple records in an RRset. For example:
807 foo.example. IN TXT "a" "b" "c"
808 foo.example. IN TXT "d" "e" "f"
810 ${lookup dnsdb{>/ txt=foo.example}} -> "a/d"
811 ${lookup dnsdb{>/; txt=foo.example}} -> "def/abc"
812 ${lookup dnsdb{>/,+ txt=foo.example}} -> "a+b+c/d+e+f"
818 1. Native DKIM support without an external library.
819 (Note that if no action to prevent it is taken, a straight upgrade will
820 result in DKIM verification of all signed incoming emails. See spec
821 for details on conditionally disabling)
823 2. Experimental DCC support via dccifd (contributed by Wolfgang Breyha).
825 3. There is now a bool{} expansion condition which maps certain strings to
826 true/false condition values (most likely of use in conjunction with the
827 and{} expansion operator).
829 4. The $spam_score, $spam_bar and $spam_report variables are now available
832 5. exim -bP now supports "macros", "macro_list" or "macro MACRO_NAME" as
833 options, provided that Exim is invoked by an admin_user.
835 6. There is a new option gnutls_compat_mode, when linked against GnuTLS,
836 which increases compatibility with older clients at the cost of decreased
837 security. Don't set this unless you need to support such clients.
839 7. There is a new expansion operator, ${randint:...} which will produce a
840 "random" number less than the supplied integer. This randomness is
841 not guaranteed to be cryptographically strong, but depending upon how
842 Exim was built may be better than the most naive schemes.
844 8. Exim now explicitly ensures that SHA256 is available when linked against
847 9. The transport_filter_timeout option now applies to SMTP transports too.
853 1. Preliminary DKIM support in Experimental.
859 1. The body_linecount and body_zerocount C variables are now exported in the
862 2. When a dnslists lookup succeeds, the key that was looked up is now placed
863 in $dnslist_matched. When the key is an IP address, it is not reversed in
864 this variable (though it is, of course, in the actual lookup). In simple
867 deny dnslists = spamhaus.example
869 the key is also available in another variable (in this case,
870 $sender_host_address). In more complicated cases, however, this is not
871 true. For example, using a data lookup might generate a dnslists lookup
874 deny dnslists = spamhaus.example/<|192.168.1.2|192.168.6.7|...
876 If this condition succeeds, the value in $dnslist_matched might be
877 192.168.6.7 (for example).
879 3. Authenticators now have a client_condition option. When Exim is running as
880 a client, it skips an authenticator whose client_condition expansion yields
881 "0", "no", or "false". This can be used, for example, to skip plain text
882 authenticators when the connection is not encrypted by a setting such as:
884 client_condition = ${if !eq{$tls_cipher}{}}
886 Note that the 4.67 documentation states that $tls_cipher contains the
887 cipher used for incoming messages. In fact, during SMTP delivery, it
888 contains the cipher used for the delivery. The same is true for
891 4. There is now a -Mvc <message-id> option, which outputs a copy of the
892 message to the standard output, in RFC 2822 format. The option can be used
893 only by an admin user.
895 5. There is now a /noupdate option for the ratelimit ACL condition. It
896 computes the rate and checks the limit as normal, but it does not update
897 the saved data. This means that, in relevant ACLs, it is possible to lookup
898 the existence of a specified (or auto-generated) ratelimit key without
899 incrementing the ratelimit counter for that key.
901 In order for this to be useful, another ACL entry must set the rate
902 for the same key somewhere (otherwise it will always be zero).
907 # Read the rate; if it doesn't exist or is below the maximum
909 deny ratelimit = 100 / 5m / strict / noupdate
910 log_message = RATE: $sender_rate / $sender_rate_period \
911 (max $sender_rate_limit)
913 [... some other logic and tests...]
915 warn ratelimit = 100 / 5m / strict / per_cmd
916 log_message = RATE UPDATE: $sender_rate / $sender_rate_period \
917 (max $sender_rate_limit)
918 condition = ${if le{$sender_rate}{$sender_rate_limit}}
922 6. The variable $max_received_linelength contains the number of bytes in the
923 longest line that was received as part of the message, not counting the
924 line termination character(s).
926 7. Host lists can now include +ignore_defer and +include_defer, analagous to
927 +ignore_unknown and +include_unknown. These options should be used with
928 care, probably only in non-critical host lists such as whitelists.
930 8. There's a new option called queue_only_load_latch, which defaults true.
931 If set false when queue_only_load is greater than zero, Exim re-evaluates
932 the load for each incoming message in an SMTP session. Otherwise, once one
933 message is queued, the remainder are also.
935 9. There is a new ACL, specified by acl_smtp_notquit, which is run in most
936 cases when an SMTP session ends without sending QUIT. However, when Exim
937 itself is is bad trouble, such as being unable to write to its log files,
938 this ACL is not run, because it might try to do things (such as write to
939 log files) that make the situation even worse.
941 Like the QUIT ACL, this new ACL is provided to make it possible to gather
942 statistics. Whatever it returns (accept or deny) is immaterial. The "delay"
943 modifier is forbidden in this ACL.
945 When the NOTQUIT ACL is running, the variable $smtp_notquit_reason is set
946 to a string that indicates the reason for the termination of the SMTP
947 connection. The possible values are:
949 acl-drop Another ACL issued a "drop" command
950 bad-commands Too many unknown or non-mail commands
951 command-timeout Timeout while reading SMTP commands
952 connection-lost The SMTP connection has been lost
953 data-timeout Timeout while reading message data
954 local-scan-error The local_scan() function crashed
955 local-scan-timeout The local_scan() function timed out
956 signal-exit SIGTERM or SIGINT
957 synchronization-error SMTP synchronization error
958 tls-failed TLS failed to start
960 In most cases when an SMTP connection is closed without having received
961 QUIT, Exim sends an SMTP response message before actually closing the
962 connection. With the exception of acl-drop, the default message can be
963 overridden by the "message" modifier in the NOTQUIT ACL. In the case of a
964 "drop" verb in another ACL, it is the message from the other ACL that is
967 10. For MySQL and PostgreSQL lookups, it is now possible to specify a list of
968 servers with individual queries. This is done by starting the query with
969 "servers=x:y:z;", where each item in the list may take one of two forms:
971 (1) If it is just a host name, the appropriate global option (mysql_servers
972 or pgsql_servers) is searched for a host of the same name, and the
973 remaining parameters (database, user, password) are taken from there.
975 (2) If it contains any slashes, it is taken as a complete parameter set.
977 The list of servers is used in exactly the same was as the global list.
978 Once a connection to a server has happened and a query has been
979 successfully executed, processing of the lookup ceases.
981 This feature is intended for use in master/slave situations where updates
982 are occurring, and one wants to update a master rather than a slave. If the
983 masters are in the list for reading, you might have:
985 mysql_servers = slave1/db/name/pw:slave2/db/name/pw:master/db/name/pw
987 In an updating lookup, you could then write
989 ${lookup mysql{servers=master; UPDATE ...}
991 If, on the other hand, the master is not to be used for reading lookups:
993 pgsql_servers = slave1/db/name/pw:slave2/db/name/pw
995 you can still update the master by
997 ${lookup pgsql{servers=master/db/name/pw; UPDATE ...}
999 11. The message_body_newlines option (default FALSE, for backwards
1000 compatibility) can be used to control whether newlines are present in
1001 $message_body and $message_body_end. If it is FALSE, they are replaced by
1008 1. There is a new log selector called smtp_no_mail, which is not included in
1009 the default setting. When it is set, a line is written to the main log
1010 whenever an accepted SMTP connection terminates without having issued a
1013 2. When an item in a dnslists list is followed by = and & and a list of IP
1014 addresses, the behaviour was not clear when the lookup returned more than
1015 one IP address. This has been solved by the addition of == and =& for "all"
1016 rather than the default "any" matching.
1018 3. Up till now, the only control over which cipher suites GnuTLS uses has been
1019 for the cipher algorithms. New options have been added to allow some of the
1020 other parameters to be varied.
1022 4. There is a new compile-time option called ENABLE_DISABLE_FSYNC. When it is
1023 set, Exim compiles a runtime option called disable_fsync.
1025 5. There is a new variable called $smtp_count_at_connection_start.
1027 6. There's a new control called no_pipelining.
1029 7. There are two new variables called $sending_ip_address and $sending_port.
1030 These are set whenever an SMTP connection to another host has been set up.
1032 8. The expansion of the helo_data option in the smtp transport now happens
1033 after the connection to the server has been made.
1035 9. There is a new expansion operator ${rfc2047d: that decodes strings that
1036 are encoded as per RFC 2047.
1038 10. There is a new log selector called "pid", which causes the current process
1039 id to be added to every log line, in square brackets, immediately after the
1042 11. Exim has been modified so that it flushes SMTP output before implementing
1043 a delay in an ACL. It also flushes the output before performing a callout,
1044 as this can take a substantial time. These behaviours can be disabled by
1045 obeying control = no_delay_flush or control = no_callout_flush,
1046 respectively, at some earlier stage of the connection.
1048 12. There are two new expansion conditions that iterate over a list. They are
1049 called forany and forall.
1051 13. There's a new global option called dsn_from that can be used to vary the
1052 contents of From: lines in bounces and other automatically generated
1053 messages ("delivery status notifications" - hence the name of the option).
1055 14. The smtp transport has a new option called hosts_avoid_pipelining.
1057 15. By default, exigrep does case-insensitive matches. There is now a -I option
1058 that makes it case-sensitive.
1060 16. A number of new features ("addresses", "map", "filter", and "reduce") have
1061 been added to string expansions to make it easier to process lists of
1062 items, typically addresses.
1064 17. There's a new ACL modifier called "continue". It does nothing of itself,
1065 and processing of the ACL always continues with the next condition or
1066 modifier. It is provided so that the side effects of expanding its argument
1069 18. It is now possible to use newline and other control characters (those with
1070 values less than 32, plus DEL) as separators in lists.
1072 19. The exigrep utility now has a -v option, which inverts the matching
1075 20. The host_find_failed option in the manualroute router can now be set to
1082 No new features were added to 4.66.
1088 No new features were added to 4.65.
1094 1. ACL variables can now be given arbitrary names, as long as they start with
1095 "acl_c" or "acl_m" (for connection variables and message variables), are at
1096 least six characters long, with the sixth character being either a digit or
1099 2. There is a new ACL modifier called log_reject_target. It makes it possible
1100 to specify which logs are used for messages about ACL rejections.
1102 3. There is a new authenticator called "dovecot". This is an interface to the
1103 authentication facility of the Dovecot POP/IMAP server, which can support a
1104 number of authentication methods.
1106 4. The variable $message_headers_raw provides a concatenation of all the
1107 messages's headers without any decoding. This is in contrast to
1108 $message_headers, which does RFC2047 decoding on the header contents.
1110 5. In a DNS black list, if two domain names, comma-separated, are given, the
1111 second is used first to do an initial check, making use of any IP value
1112 restrictions that are set. If there is a match, the first domain is used,
1113 without any IP value restrictions, to get the TXT record.
1115 6. All authenticators now have a server_condition option.
1117 7. There is a new command-line option called -Mset. It is useful only in
1118 conjunction with -be (that is, when testing string expansions). It must be
1119 followed by a message id; Exim loads the given message from its spool
1120 before doing the expansions.
1122 8. Another similar new command-line option is called -bem. It operates like
1123 -be except that it must be followed by the name of a file that contains a
1126 9. When an address is delayed because of a 4xx response to a RCPT command, it
1127 is now the combination of sender and recipient that is delayed in
1128 subsequent queue runs until its retry time is reached.
1130 10. Unary negation and the bitwise logical operators and, or, xor, not, and
1131 shift, have been added to the eval: and eval10: expansion items.
1133 11. The variables $interface_address and $interface_port have been renamed
1134 as $received_ip_address and $received_port, to make it clear that they
1135 relate to message reception rather than delivery. (The old names remain
1136 available for compatibility.)
1138 12. The "message" modifier can now be used on "accept" and "discard" acl verbs
1139 to vary the message that is sent when an SMTP command is accepted.
1145 1. There is a new Boolean option called filter_prepend_home for the redirect
1148 2. There is a new acl, set by acl_not_smtp_start, which is run right at the
1149 start of receiving a non-SMTP message, before any of the message has been
1152 3. When an SMTP error message is specified in a "message" modifier in an ACL,
1153 or in a :fail: or :defer: message in a redirect router, Exim now checks the
1154 start of the message for an SMTP error code.
1156 4. There is a new parameter for LDAP lookups called "referrals", which takes
1157 one of the settings "follow" (the default) or "nofollow".
1159 5. Version 20070721.2 of exipick now included, offering these new options:
1161 After all other sorting options have bee processed, reverse order
1162 before displaying messages (-R is synonym).
1164 Randomize order of matching messages before displaying.
1166 Instead of displaying the matching messages, display the sum
1168 --sort <variable>[,<variable>...]
1169 Before displaying matching messages, sort the messages according to
1170 each messages value for each variable.
1172 Negate the value for every test (returns inverse output from the
1173 same criteria without --not).
1179 1. The ${readsocket expansion item now supports Internet domain sockets as well
1180 as Unix domain sockets. If the first argument begins "inet:", it must be of
1181 the form "inet:host:port". The port is mandatory; it may be a number or the
1182 name of a TCP port in /etc/services. The host may be a name, or it may be an
1183 IP address. An ip address may optionally be enclosed in square brackets.
1184 This is best for IPv6 addresses. For example:
1186 ${readsocket{inet:[::1]:1234}{<request data>}...
1188 Only a single host name may be given, but if looking it up yield more than
1189 one IP address, they are each tried in turn until a connection is made. Once
1190 a connection has been made, the behaviour is as for ${readsocket with a Unix
1193 2. If a redirect router sets up file or pipe deliveries for more than one
1194 incoming address, and the relevant transport has batch_max set greater than
1195 one, a batch delivery now occurs.
1197 3. The appendfile transport has a new option called maildirfolder_create_regex.
1198 Its value is a regular expression. For a maildir delivery, this is matched
1199 against the maildir directory; if it matches, Exim ensures that a
1200 maildirfolder file is created alongside the new, cur, and tmp directories.
1206 The documentation is up-to-date for the 4.61 release. Major new features since
1207 the 4.60 release are:
1209 . An option called disable_ipv6, to disable the use of IPv6 completely.
1211 . An increase in the number of ACL variables to 20 of each type.
1213 . A change to use $auth1, $auth2, and $auth3 in authenticators instead of $1,
1214 $2, $3, (though those are still set) because the numeric variables get used
1215 for other things in complicated expansions.
1217 . The default for rfc1413_query_timeout has been changed from 30s to 5s.
1219 . It is possible to use setclassresources() on some BSD OS to control the
1220 resources used in pipe deliveries.
1222 . A new ACL modifier called add_header, which can be used with any verb.
1224 . More errors are detectable in retry rules.
1226 There are a number of other additions too.
1232 The documentation is up-to-date for the 4.60 release. Major new features since
1233 the 4.50 release are:
1235 . Support for SQLite.
1237 . Support for IGNOREQUOTA in LMTP.
1239 . Extensions to the "submission mode" features.
1241 . Support for Client SMTP Authorization (CSA).
1243 . Support for ratelimiting hosts and users.
1245 . New expansion items to help with the BATV "prvs" scheme.
1247 . A "match_ip" condition, that matches an IP address against a list.
1249 There are many more minor changes.
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