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. Allow relative config file names for ".include"
18 1. The new perl_taintmode option allows to run the embedded perl
19 interpreter in taint mode.
21 2. New log_selector: dnssec, adds a "DS" tag to acceptance and delivery lines.
23 3. Speculative debugging, via a "kill" option to the "control=debug" ACL
26 4. New expansion item ${sha3:<string>} / ${sha3_<N>:<string>}.
27 N can be 224, 256 (default), 384, 512.
28 With GnuTLS 3.5.0 or later, only.
30 5. Facility for named queues: A command-line argument can specify
31 the queue name for a queue operation, and an ACL modifier can set
32 the queue to be used for a message. A $queue_name variable gives
35 6. New expansion operators base32/base32d.
37 7. The CHUNKING ESMTP extension from RFC 3030. May give some slight
38 performance increase and network load decrease. Main config option
39 chunking_advertise_hosts, and smtp transport option hosts_try_chunking
42 8. LMDB lookup support, as Experimental. Patch supplied by Andrew Colin Kissa.
44 9. Expansion operator escape8bit, like escape but not touching newline etc..
46 10. Feature macros, generated from compile options. All start with "_HAVE_"
47 and go on with some roughly recognisable name. Driver macros, for
48 router, transport and authentication drivers; names starting with "_DRIVER_".
49 Option macros, for each configuration-file option; all start with "_OPT_".
50 Use the "-bP macros" command-line option to see what is present.
52 11. Integer values for options can take a "G" multiplier.
54 12. defer=pass option for the ACL control cutthrough_delivery, to reflect 4xx
55 returns from the target back to the initiator, rather than spooling the
58 13. New built-in constants available for tls_dhparam and default changed.
60 14. If built with EXPERIMENTAL_QUEUEFILE, a queuefile transport, for writing
61 out copies of the message spool files for use by 3rd-party scanners.
63 15. A new option on the smtp transport, hosts_try_fastopen. If the system
64 supports it (on Linux it must be enabled in the kernel by the sysadmin)
65 try to use RFC 7413 "TCP Fast Open". No data is sent on the SYN segment
66 but it permits a peer that also supports the facility to send its SMTP
67 banner immediately after the SYN,ACK segment rather then waiting for
68 another ACK - so saving up to one roundtrip time. Because it requires
69 previous communication with the peer (we save a cookie from it) this
70 will only become active on frequently-contacted destinations.
72 16. A new syslog_pid option to suppress PID duplication in syslog lines.
78 1. The ACL conditions regex and mime_regex now capture substrings
79 into numeric variables $regex1 to 9, like the "match" expansion condition.
81 2. New $callout_address variable records the address used for a spam=,
82 malware= or verify= callout.
84 3. Transports now take a "max_parallel" option, to limit concurrency.
86 4. Expansion operators ${ipv6norm:<string>} and ${ipv6denorm:<string>}.
87 The latter expands to a 8-element colon-sep set of hex digits including
88 leading zeroes. A trailing ipv4-style dotted-decimal set is converted
89 to hex. Pure ipv4 addresses are converted to IPv4-mapped IPv6.
90 The former operator strips leading zeroes and collapses the longest
91 set of 0-groups to a double-colon.
93 5. New "-bP config" support, to dump the effective configuration.
95 6. New $dkim_key_length variable.
97 7. New base64d and base64 expansion items (the existing str2b64 being a
98 synonym of the latter). Add support in base64 for certificates.
100 8. New main configuration option "bounce_return_linesize_limit" to
101 avoid oversize bodies in bounces. The default value matches RFC
104 9. New $initial_cwd expansion variable.
110 1. Support for using the system standard CA bundle.
112 2. New expansion items $config_file, $config_dir, containing the file
113 and directory name of the main configuration file. Also $exim_version.
115 3. New "malware=" support for Avast.
117 4. New "spam=" variant option for Rspamd.
119 5. Assorted options on malware= and spam= scanners.
121 6. A command-line option to write a comment into the logfile.
123 7. If built with EXPERIMENTAL_SOCKS feature enabled, the smtp transport can
124 be configured to make connections via socks5 proxies.
126 8. If built with EXPERIMENTAL_INTERNATIONAL, support is included for
127 the transmission of UTF-8 envelope addresses.
129 9. If built with EXPERIMENTAL_INTERNATIONAL, an expansion item for a commonly
130 used encoding of Maildir folder names.
132 10. A logging option for slow DNS lookups.
134 11. New ${env {<variable>}} expansion.
136 12. A non-SMTP authenticator using information from TLS client certificates.
138 13. Main option "tls_eccurve" for selecting an Elliptic Curve for TLS.
139 Patch originally by Wolfgang Breyha.
141 14. Main option "dns_trust_aa" for trusting your local nameserver at the
142 same level as DNSSEC.
148 1. If built with EXPERIMENTAL_DANE feature enabled, Exim will follow the
149 DANE SMTP draft to assess a secure chain of trust of the certificate
150 used to establish the TLS connection based on a TLSA record in the
151 domain of the sender.
153 2. The EXPERIMENTAL_TPDA feature has been renamed to EXPERIMENTAL_EVENT
154 and several new events have been created. The reason is because it has
155 been expanded beyond just firing events during the transport phase. Any
156 existing TPDA transport options will have to be rewritten to use a new
157 $event_name expansion variable in a condition. Refer to the
158 experimental-spec.txt for details and examples.
160 3. The EXPERIMENTAL_CERTNAMES features is an enhancement to verify that
161 server certs used for TLS match the result of the MX lookup. It does
162 not use the same mechanism as DANE.
172 1. If built with the EXPERIMENTAL_PROXY feature enabled, Exim can be
173 configured to expect an initial header from a proxy that will make the
174 actual external source IP:host be used in exim instead of the IP of the
175 proxy that is connecting to it.
177 2. New verify option header_names_ascii, which will check to make sure
178 there are no non-ASCII characters in header names. Exim itself handles
179 those non-ASCII characters, but downstream apps may not, so Exim can
180 detect and reject if those characters are present.
182 3. New expansion operator ${utf8clean:string} to replace malformed UTF8
183 codepoints with valid ones.
185 4. New malware type "sock". Talks over a Unix or TCP socket, sending one
186 command line and matching a regex against the return data for trigger
187 and a second regex to extract malware_name. The mail spoolfile name can
188 be included in the command line.
190 5. The smtp transport now supports options "tls_verify_hosts" and
191 "tls_try_verify_hosts". If either is set the certificate verification
192 is split from the encryption operation. The default remains that a failed
193 verification cancels the encryption.
195 6. New SERVERS override of default ldap server list. In the ACLs, an ldap
196 lookup can now set a list of servers to use that is different from the
199 7. New command-line option -C for exiqgrep to specify alternate exim.conf
200 file when searching the queue.
202 8. OCSP now supports GnuTLS also, if you have version 3.1.3 or later of that.
204 9. Support for DNSSEC on outbound connections.
206 10. New variables "tls_(in,out)_(our,peer)cert" and expansion item
207 "certextract" to extract fields from them. Hash operators md5 and sha1
208 work over them for generating fingerprints, and a new sha256 operator
211 11. PRDR is now supported dy default.
213 12. OCSP stapling is now supported by default.
215 13. If built with the EXPERIMENTAL_DSN feature enabled, Exim will output
216 Delivery Status Notification messages in MIME format, and negotiate
217 DSN features per RFC 3461.
223 1. New command-line option -bI:sieve will list all supported sieve extensions
224 of this Exim build on standard output, one per line.
225 ManageSieve (RFC 5804) providers managing scripts for use by Exim should
226 query this to establish the correct list to include in the protocol's
227 SIEVE capability line.
229 2. If the -n option is combined with the -bP option, then the name of an
230 emitted option is not output, only the value (if visible to you).
231 For instance, "exim -n -bP pid_file_path" should just emit a pathname
232 followed by a newline, and no other text.
234 3. When built with SUPPORT_TLS and USE_GNUTLS, the SMTP transport driver now
235 has a "tls_dh_min_bits" option, to set the minimum acceptable number of
236 bits in the Diffie-Hellman prime offered by a server (in DH ciphersuites)
237 acceptable for security. (Option accepted but ignored if using OpenSSL).
238 Defaults to 1024, the old value. May be lowered only to 512, or raised as
239 far as you like. Raising this may hinder TLS interoperability with other
240 sites and is not currently recommended. Lowering this will permit you to
241 establish a TLS session which is not as secure as you might like.
243 Unless you really know what you are doing, leave it alone.
245 4. If not built with DISABLE_DNSSEC, Exim now has the main option
246 dns_dnssec_ok; if set to 1 then Exim will initialise the resolver library
247 to send the DO flag to your recursive resolver. If you have a recursive
248 resolver, which can set the Authenticated Data (AD) flag in results, Exim
249 can now detect this. Exim does not perform validation itself, instead
250 relying upon a trusted path to the resolver.
252 Current status: work-in-progress; $sender_host_dnssec variable added.
254 5. DSCP support for outbound connections: on a transport using the smtp driver,
255 set "dscp = ef", for instance, to cause the connections to have the relevant
256 DSCP (IPv4 TOS or IPv6 TCLASS) value in the header.
258 Similarly for inbound connections, there is a new control modifier, dscp,
259 so "warn control = dscp/ef" in the connect ACL, or after authentication.
261 Supported values depend upon system libraries. "exim -bI:dscp" to list the
262 ones Exim knows of. You can also set a raw number 0..0x3F.
264 6. The -G command-line flag is no longer ignored; it is now equivalent to an
265 ACL setting "control = suppress_local_fixups". The -L command-line flag
266 is now accepted and forces use of syslog, with the provided tag as the
267 process name. A few other flags used by Sendmail are now accepted and
270 7. New cutthrough routing feature. Requested by a "control = cutthrough_delivery"
271 ACL modifier; works for single-recipient mails which are received on and
272 deliverable via SMTP. Using the connection made for a recipient verify,
273 if requested before the verify, or a new one made for the purpose while
274 the inbound connection is still active. The bulk of the mail item is copied
275 direct from the inbound socket to the outbound (as well as the spool file).
276 When the source notifies the end of data, the data acceptance by the destination
277 is negotiated before the acceptance is sent to the source. If the destination
278 does not accept the mail item, for example due to content-scanning, the item
279 is not accepted from the source and therefore there is no need to generate
280 a bounce mail. This is of benefit when providing a secondary-MX service.
281 The downside is that delays are under the control of the ultimate destination
284 The Received-by: header on items delivered by cutthrough is generated
285 early in reception rather than at the end; this will affect any timestamp
286 included. The log line showing delivery is recorded before that showing
287 reception; it uses a new ">>" tag instead of "=>".
289 To support the feature, verify-callout connections can now use ESMTP and TLS.
290 The usual smtp transport options are honoured, plus a (new, default everything)
291 hosts_verify_avoid_tls.
293 New variable families named tls_in_cipher, tls_out_cipher etc. are introduced
294 for specific access to the information for each connection. The old names
295 are present for now but deprecated.
297 Not yet supported: IGNOREQUOTA, SIZE, PIPELINING.
299 8. New expansion operators ${listnamed:name} to get the content of a named list
300 and ${listcount:string} to count the items in a list.
302 9. New global option "gnutls_allow_auto_pkcs11", defaults false. The GnuTLS
303 rewrite in 4.80 combines with GnuTLS 2.12.0 or later, to autoload PKCS11
304 modules. For some situations this is desirable, but we expect admin in
305 those situations to know they want the feature. More commonly, it means
306 that GUI user modules get loaded and are broken by the setuid Exim being
307 unable to access files specified in environment variables and passed
308 through, thus breakage. So we explicitly inhibit the PKCS11 initialisation
309 unless this new option is set.
311 Some older OS's with earlier versions of GnuTLS might not have pkcs11 ability,
312 so have also added a build option which can be used to build Exim with GnuTLS
313 but without trying to use any kind of PKCS11 support. Uncomment this in the
316 AVOID_GNUTLS_PKCS11=yes
318 10. The "acl = name" condition on an ACL now supports optional arguments.
319 New expansion item "${acl {name}{arg}...}" and expansion condition
320 "acl {{name}{arg}...}" are added. In all cases up to nine arguments
321 can be used, appearing in $acl_arg1 to $acl_arg9 for the called ACL.
322 Variable $acl_narg contains the number of arguments. If the ACL sets
323 a "message =" value this becomes the result of the expansion item,
324 or the value of $value for the expansion condition. If the ACL returns
325 accept the expansion condition is true; if reject, false. A defer
326 return results in a forced fail.
328 11. Routers and transports can now have multiple headers_add and headers_remove
329 option lines. The concatenated list is used.
331 12. New ACL modifier "remove_header" can remove headers before message gets
332 handled by routers/transports.
334 13. New dnsdb lookup pseudo-type "a+". A sequence of "a6" (if configured),
335 "aaaa" and "a" lookups is done and the full set of results returned.
337 14. New expansion variable $headers_added with content from ACL add_header
338 modifier (but not yet added to message).
340 15. New 8bitmime status logging option for received messages. Log field "M8S".
342 16. New authenticated_sender logging option, adding to log field "A".
344 17. New expansion variables $router_name and $transport_name. Useful
345 particularly for debug_print as -bt command-line option does not
346 require privilege whereas -d does.
348 18. If built with EXPERIMENTAL_PRDR, per-recipient data responses per a
349 proposed extension to SMTP from Eric Hall.
351 19. The pipe transport has gained the force_command option, to allow
352 decorating commands from user .forward pipe aliases with prefix
353 wrappers, for instance.
355 20. Callout connections can now AUTH; the same controls as normal delivery
358 21. Support for DMARC, using opendmarc libs, can be enabled. It adds new
359 options: dmarc_forensic_sender, dmarc_history_file, and dmarc_tld_file.
360 It adds new expansion variables $dmarc_ar_header, $dmarc_status,
361 $dmarc_status_text, and $dmarc_used_domain. It adds a new acl modifier
362 dmarc_status. It adds new control flags dmarc_disable_verify and
363 dmarc_enable_forensic.
365 22. Add expansion variable $authenticated_fail_id, which is the username
366 provided to the authentication method which failed. It is available
367 for use in subsequent ACL processing (typically quit or notquit ACLs).
369 23. New ACL modifier "udpsend" can construct a UDP packet to send to a given
372 24. New ${hexquote:..string..} expansion operator converts non-printable
373 characters in the string to \xNN form.
375 25. Experimental TPDA (Transport Post Delivery Action) function added.
376 Patch provided by Axel Rau.
378 26. Experimental Redis lookup added. Patch provided by Warren Baker.
384 1. New authenticator driver, "gsasl". Server-only (at present).
385 This is a SASL interface, licensed under GPL, which can be found at
386 http://www.gnu.org/software/gsasl/.
387 This system does not provide sources of data for authentication, so
388 careful use needs to be made of the conditions in Exim.
390 2. New authenticator driver, "heimdal_gssapi". Server-only.
391 A replacement for using cyrus_sasl with Heimdal, now that $KRB5_KTNAME
392 is no longer honoured for setuid programs by Heimdal. Use the
393 "server_keytab" option to point to the keytab.
395 3. The "pkg-config" system can now be used when building Exim to reference
396 cflags and library information for lookups and authenticators, rather
397 than having to update "CFLAGS", "AUTH_LIBS", "LOOKUP_INCLUDE" and
398 "LOOKUP_LIBS" directly. Similarly for handling the TLS library support
399 without adjusting "TLS_INCLUDE" and "TLS_LIBS".
401 In addition, setting PCRE_CONFIG=yes will query the pcre-config tool to
402 find the headers and libraries for PCRE.
404 4. New expansion variable $tls_bits.
406 5. New lookup type, "dbmjz". Key is an Exim list, the elements of which will
407 be joined together with ASCII NUL characters to construct the key to pass
408 into the DBM library. Can be used with gsasl to access sasldb2 files as
411 6. OpenSSL now supports TLS1.1 and TLS1.2 with OpenSSL 1.0.1.
413 Avoid release 1.0.1a if you can. Note that the default value of
414 "openssl_options" is no longer "+dont_insert_empty_fragments", as that
415 increased susceptibility to attack. This may still have interoperability
416 implications for very old clients (see version 4.31 change 37) but
417 administrators can choose to make the trade-off themselves and restore
418 compatibility at the cost of session security.
420 7. Use of the new expansion variable $tls_sni in the main configuration option
421 tls_certificate will cause Exim to re-expand the option, if the client
422 sends the TLS Server Name Indication extension, to permit choosing a
423 different certificate; tls_privatekey will also be re-expanded. You must
424 still set these options to expand to valid files when $tls_sni is not set.
426 The SMTP Transport has gained the option tls_sni, which will set a hostname
427 for outbound TLS sessions, and set $tls_sni too.
429 A new log_selector, +tls_sni, has been added, to log received SNI values
430 for Exim as a server.
432 8. The existing "accept_8bitmime" option now defaults to true. This means
433 that Exim is deliberately not strictly RFC compliant. We're following
434 Dan Bernstein's advice in http://cr.yp.to/smtp/8bitmime.html by default.
435 Those who disagree, or know that they are talking to mail servers that,
436 even today, are not 8-bit clean, need to turn off this option.
438 9. Exim can now be started with -bw (with an optional timeout, given as
439 -bw<timespec>). With this, stdin at startup is a socket that is
440 already listening for connections. This has a more modern name of
441 "socket activation", but forcing the activated socket to fd 0. We're
442 interested in adding more support for modern variants.
444 10. ${eval } now uses 64-bit values on supporting platforms. A new "G" suffix
445 for numbers indicates multiplication by 1024^3.
447 11. The GnuTLS support has been revamped; the three options gnutls_require_kx,
448 gnutls_require_mac & gnutls_require_protocols are no longer supported.
449 tls_require_ciphers is now parsed by gnutls_priority_init(3) as a priority
450 string, documentation for which is at:
451 http://www.gnutls.org/manual/html_node/Priority-Strings.html
453 SNI support has been added to Exim's GnuTLS integration too.
455 For sufficiently recent GnuTLS libraries, ${randint:..} will now use
456 gnutls_rnd(), asking for GNUTLS_RND_NONCE level randomness.
458 12. With OpenSSL, if built with EXPERIMENTAL_OCSP, a new option tls_ocsp_file
459 is now available. If the contents of the file are valid, then Exim will
460 send that back in response to a TLS status request; this is OCSP Stapling.
461 Exim will not maintain the contents of the file in any way: administrators
462 are responsible for ensuring that it is up-to-date.
464 See "experimental-spec.txt" for more details.
466 13. ${lookup dnsdb{ }} supports now SPF record types. They are handled
467 identically to TXT record lookups.
469 14. New expansion variable $tod_epoch_l for higher-precision time.
471 15. New global option tls_dh_max_bits, defaulting to current value of NSS
472 hard-coded limit of DH ephemeral bits, to fix interop problems caused by
473 GnuTLS 2.12 library recommending a bit count higher than NSS supports.
475 16. tls_dhparam now used by both OpenSSL and GnuTLS, can be path or identifier.
476 Option can now be a path or an identifier for a standard prime.
477 If unset, we use the DH prime from section 2.2 of RFC 5114, "ike23".
478 Set to "historic" to get the old GnuTLS behaviour of auto-generated DH
481 17. SSLv2 now disabled by default in OpenSSL. (Never supported by GnuTLS).
482 Use "openssl_options -no_sslv2" to re-enable support, if your OpenSSL
483 install was not built with OPENSSL_NO_SSL2 ("no-ssl2").
489 1. New options for the ratelimit ACL condition: /count= and /unique=.
490 The /noupdate option has been replaced by a /readonly option.
492 2. The SMTP transport's protocol option may now be set to "smtps", to
493 use SSL-on-connect outbound.
495 3. New variable $av_failed, set true if the AV scanner deferred; ie, when
496 there is a problem talking to the AV scanner, or the AV scanner running.
498 4. New expansion conditions, "inlist" and "inlisti", which take simple lists
499 and check if the search item is a member of the list. This does not
500 support named lists, but does subject the list part to string expansion.
502 5. Unless the new EXPAND_LISTMATCH_RHS build option is set when Exim was
503 built, Exim no longer performs string expansion on the second string of
504 the match_* expansion conditions: "match_address", "match_domain",
505 "match_ip" & "match_local_part". Named lists can still be used.
511 1. The global option "dns_use_edns0" may be set to coerce EDNS0 usage on
512 or off in the resolver library.
518 1. In addition to the existing LDAP and LDAP/SSL ("ldaps") support, there
519 is now LDAP/TLS support, given sufficiently modern OpenLDAP client
520 libraries. The following global options have been added in support of
521 this: ldap_ca_cert_dir, ldap_ca_cert_file, ldap_cert_file, ldap_cert_key,
522 ldap_cipher_suite, ldap_require_cert, ldap_start_tls.
524 2. The pipe transport now takes a boolean option, "freeze_signal", default
525 false. When true, if the external delivery command exits on a signal then
526 Exim will freeze the message in the queue, instead of generating a bounce.
528 3. Log filenames may now use %M as an escape, instead of %D (still available).
529 The %M pattern expands to yyyymm, providing month-level resolution.
531 4. The $message_linecount variable is now updated for the maildir_tag option,
532 in the same way as $message_size, to reflect the real number of lines,
533 including any header additions or removals from transport.
535 5. When contacting a pool of SpamAssassin servers configured in spamd_address,
536 Exim now selects entries randomly, to better scale in a cluster setup.
542 1. SECURITY FIX: privilege escalation flaw fixed. On Linux (and only Linux)
543 the flaw permitted the Exim run-time user to cause root to append to
544 arbitrary files of the attacker's choosing, with the content based
545 on content supplied by the attacker.
547 2. Exim now supports loading some lookup types at run-time, using your
548 platform's dlopen() functionality. This has limited platform support
549 and the intention is not to support every variant, it's limited to
550 dlopen(). This permits the main Exim binary to not be linked against
551 all the libraries needed for all the lookup types.
557 NOTE: this version is not guaranteed backwards-compatible, please read the
558 items below carefully
560 1. A new main configuration option, "openssl_options", is available if Exim
561 is built with SSL support provided by OpenSSL. The option allows
562 administrators to specify OpenSSL options to be used on connections;
563 typically this is to set bug compatibility features which the OpenSSL
564 developers have not enabled by default. There may be security
565 consequences for certain options, so these should not be changed
568 2. A new pipe transport option, "permit_coredumps", may help with problem
569 diagnosis in some scenarios. Note that Exim is typically installed as
570 a setuid binary, which on most OSes will inhibit coredumps by default,
571 so that safety mechanism would have to be overridden for this option to
572 be able to take effect.
574 3. ClamAV 0.95 is now required for ClamAV support in Exim, unless
575 Local/Makefile sets: WITH_OLD_CLAMAV_STREAM=yes
576 Note that this switches Exim to use a new API ("INSTREAM") and a future
577 release of ClamAV will remove support for the old API ("STREAM").
579 The av_scanner option, when set to "clamd", now takes an optional third
580 part, "local", which causes Exim to pass a filename to ClamAV instead of
581 the file content. This is the same behaviour as when clamd is pointed at
582 a Unix-domain socket. For example:
584 av_scanner = clamd:192.0.2.3 1234:local
586 ClamAV's ExtendedDetectionInfo response format is now handled.
588 4. There is now a -bmalware option, restricted to admin users. This option
589 takes one parameter, a filename, and scans that file with Exim's
590 malware-scanning framework. This is intended purely as a debugging aid
591 to ensure that Exim's scanning is working, not to replace other tools.
592 Note that the ACL framework is not invoked, so if av_scanner references
593 ACL variables without a fallback then this will fail.
595 5. There is a new expansion operator, "reverse_ip", which will reverse IP
596 addresses; IPv4 into dotted quad, IPv6 into dotted nibble. Examples:
598 ${reverse_ip:192.0.2.4}
600 ${reverse_ip:2001:0db8:c42:9:1:abcd:192.0.2.3}
601 -> 3.0.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2
603 6. There is a new ACL control called "debug", to enable debug logging.
604 This allows selective logging of certain incoming transactions within
605 production environments, with some care. It takes two options, "tag"
606 and "opts"; "tag" is included in the filename of the log and "opts"
607 is used as per the -d<options> command-line option. Examples, which
608 don't all make sense in all contexts:
611 control = debug/tag=.$sender_host_address
612 control = debug/opts=+expand+acl
613 control = debug/tag=.$message_exim_id/opts=+expand
615 7. It has always been implicit in the design and the documentation that
616 "the Exim user" is not root. src/EDITME said that using root was
617 "very strongly discouraged". This is not enough to keep people from
618 shooting themselves in the foot in days when many don't configure Exim
619 themselves but via package build managers. The security consequences of
620 running various bits of network code are severe if there should be bugs in
621 them. As such, the Exim user may no longer be root. If configured
622 statically, Exim will refuse to build. If configured as ref:user then Exim
623 will exit shortly after start-up. If you must shoot yourself in the foot,
624 then henceforth you will have to maintain your own local patches to strip
627 8. There is a new expansion condition, bool_lax{}. Where bool{} uses the ACL
628 condition logic to determine truth/failure and will fail to expand many
629 strings, bool_lax{} uses the router condition logic, where most strings
631 Note: bool{00} is false, bool_lax{00} is true.
633 9. Routers now support multiple "condition" tests.
635 10. There is now a runtime configuration option "tcp_wrappers_daemon_name".
636 Setting this allows an admin to define which entry in the tcpwrappers
637 config file will be used to control access to the daemon. This option
638 is only available when Exim is built with USE_TCP_WRAPPERS. The
639 default value is set at build time using the TCP_WRAPPERS_DAEMON_NAME
642 11. [POSSIBLE CONFIG BREAKAGE] The default value for system_filter_user is now
643 the Exim run-time user, instead of root.
645 12. [POSSIBLE CONFIG BREAKAGE] ALT_CONFIG_ROOT_ONLY is no longer optional and
646 is forced on. This is mitigated by the new build option
647 TRUSTED_CONFIG_LIST which defines a list of configuration files which
648 are trusted; one per line. If a config file is owned by root and matches
649 a pathname in the list, then it may be invoked by the Exim build-time
650 user without Exim relinquishing root privileges.
652 13. [POSSIBLE CONFIG BREAKAGE] The Exim user is no longer automatically
653 trusted to supply -D<Macro[=Value]> overrides on the command-line. Going
654 forward, we recommend using TRUSTED_CONFIG_LIST with shim configs that
655 include the main config. As a transition mechanism, we are temporarily
656 providing a work-around: the new build option WHITELIST_D_MACROS provides
657 a colon-separated list of macro names which may be overridden by the Exim
658 run-time user. The values of these macros are constrained to the regex
659 ^[A-Za-z0-9_/.-]*$ (which explicitly does allow for empty values).
665 1. TWO SECURITY FIXES: one relating to mail-spools which are globally
666 writable, the other to locking of MBX folders (not mbox).
668 2. MySQL stored procedures are now supported.
670 3. The dkim_domain transport option is now a list, not a single string, and
671 messages will be signed for each element in the list (discarding
674 4. The 4.70 release unexpectedly changed the behaviour of dnsdb TXT lookups
675 in the presence of multiple character strings within the RR. Prior to 4.70,
676 only the first string would be returned. The dnsdb lookup now, by default,
677 preserves the pre-4.70 semantics, but also now takes an extended output
678 separator specification. The separator can be followed by a semicolon, to
679 concatenate the individual text strings together with no join character,
680 or by a comma and a second separator character, in which case the text
681 strings within a TXT record are joined on that second character.
682 Administrators are reminded that DNS provides no ordering guarantees
683 between multiple records in an RRset. For example:
685 foo.example. IN TXT "a" "b" "c"
686 foo.example. IN TXT "d" "e" "f"
688 ${lookup dnsdb{>/ txt=foo.example}} -> "a/d"
689 ${lookup dnsdb{>/; txt=foo.example}} -> "def/abc"
690 ${lookup dnsdb{>/,+ txt=foo.example}} -> "a+b+c/d+e+f"
696 1. Native DKIM support without an external library.
697 (Note that if no action to prevent it is taken, a straight upgrade will
698 result in DKIM verification of all signed incoming emails. See spec
699 for details on conditionally disabling)
701 2. Experimental DCC support via dccifd (contributed by Wolfgang Breyha).
703 3. There is now a bool{} expansion condition which maps certain strings to
704 true/false condition values (most likely of use in conjunction with the
705 and{} expansion operator).
707 4. The $spam_score, $spam_bar and $spam_report variables are now available
710 5. exim -bP now supports "macros", "macro_list" or "macro MACRO_NAME" as
711 options, provided that Exim is invoked by an admin_user.
713 6. There is a new option gnutls_compat_mode, when linked against GnuTLS,
714 which increases compatibility with older clients at the cost of decreased
715 security. Don't set this unless you need to support such clients.
717 7. There is a new expansion operator, ${randint:...} which will produce a
718 "random" number less than the supplied integer. This randomness is
719 not guaranteed to be cryptographically strong, but depending upon how
720 Exim was built may be better than the most naive schemes.
722 8. Exim now explicitly ensures that SHA256 is available when linked against
725 9. The transport_filter_timeout option now applies to SMTP transports too.
731 1. Preliminary DKIM support in Experimental.
737 1. The body_linecount and body_zerocount C variables are now exported in the
740 2. When a dnslists lookup succeeds, the key that was looked up is now placed
741 in $dnslist_matched. When the key is an IP address, it is not reversed in
742 this variable (though it is, of course, in the actual lookup). In simple
745 deny dnslists = spamhaus.example
747 the key is also available in another variable (in this case,
748 $sender_host_address). In more complicated cases, however, this is not
749 true. For example, using a data lookup might generate a dnslists lookup
752 deny dnslists = spamhaus.example/<|192.168.1.2|192.168.6.7|...
754 If this condition succeeds, the value in $dnslist_matched might be
755 192.168.6.7 (for example).
757 3. Authenticators now have a client_condition option. When Exim is running as
758 a client, it skips an authenticator whose client_condition expansion yields
759 "0", "no", or "false". This can be used, for example, to skip plain text
760 authenticators when the connection is not encrypted by a setting such as:
762 client_condition = ${if !eq{$tls_cipher}{}}
764 Note that the 4.67 documentation states that $tls_cipher contains the
765 cipher used for incoming messages. In fact, during SMTP delivery, it
766 contains the cipher used for the delivery. The same is true for
769 4. There is now a -Mvc <message-id> option, which outputs a copy of the
770 message to the standard output, in RFC 2822 format. The option can be used
771 only by an admin user.
773 5. There is now a /noupdate option for the ratelimit ACL condition. It
774 computes the rate and checks the limit as normal, but it does not update
775 the saved data. This means that, in relevant ACLs, it is possible to lookup
776 the existence of a specified (or auto-generated) ratelimit key without
777 incrementing the ratelimit counter for that key.
779 In order for this to be useful, another ACL entry must set the rate
780 for the same key somewhere (otherwise it will always be zero).
785 # Read the rate; if it doesn't exist or is below the maximum
787 deny ratelimit = 100 / 5m / strict / noupdate
788 log_message = RATE: $sender_rate / $sender_rate_period \
789 (max $sender_rate_limit)
791 [... some other logic and tests...]
793 warn ratelimit = 100 / 5m / strict / per_cmd
794 log_message = RATE UPDATE: $sender_rate / $sender_rate_period \
795 (max $sender_rate_limit)
796 condition = ${if le{$sender_rate}{$sender_rate_limit}}
800 6. The variable $max_received_linelength contains the number of bytes in the
801 longest line that was received as part of the message, not counting the
802 line termination character(s).
804 7. Host lists can now include +ignore_defer and +include_defer, analagous to
805 +ignore_unknown and +include_unknown. These options should be used with
806 care, probably only in non-critical host lists such as whitelists.
808 8. There's a new option called queue_only_load_latch, which defaults true.
809 If set false when queue_only_load is greater than zero, Exim re-evaluates
810 the load for each incoming message in an SMTP session. Otherwise, once one
811 message is queued, the remainder are also.
813 9. There is a new ACL, specified by acl_smtp_notquit, which is run in most
814 cases when an SMTP session ends without sending QUIT. However, when Exim
815 itself is is bad trouble, such as being unable to write to its log files,
816 this ACL is not run, because it might try to do things (such as write to
817 log files) that make the situation even worse.
819 Like the QUIT ACL, this new ACL is provided to make it possible to gather
820 statistics. Whatever it returns (accept or deny) is immaterial. The "delay"
821 modifier is forbidden in this ACL.
823 When the NOTQUIT ACL is running, the variable $smtp_notquit_reason is set
824 to a string that indicates the reason for the termination of the SMTP
825 connection. The possible values are:
827 acl-drop Another ACL issued a "drop" command
828 bad-commands Too many unknown or non-mail commands
829 command-timeout Timeout while reading SMTP commands
830 connection-lost The SMTP connection has been lost
831 data-timeout Timeout while reading message data
832 local-scan-error The local_scan() function crashed
833 local-scan-timeout The local_scan() function timed out
834 signal-exit SIGTERM or SIGINT
835 synchronization-error SMTP synchronization error
836 tls-failed TLS failed to start
838 In most cases when an SMTP connection is closed without having received
839 QUIT, Exim sends an SMTP response message before actually closing the
840 connection. With the exception of acl-drop, the default message can be
841 overridden by the "message" modifier in the NOTQUIT ACL. In the case of a
842 "drop" verb in another ACL, it is the message from the other ACL that is
845 10. For MySQL and PostgreSQL lookups, it is now possible to specify a list of
846 servers with individual queries. This is done by starting the query with
847 "servers=x:y:z;", where each item in the list may take one of two forms:
849 (1) If it is just a host name, the appropriate global option (mysql_servers
850 or pgsql_servers) is searched for a host of the same name, and the
851 remaining parameters (database, user, password) are taken from there.
853 (2) If it contains any slashes, it is taken as a complete parameter set.
855 The list of servers is used in exactly the same was as the global list.
856 Once a connection to a server has happened and a query has been
857 successfully executed, processing of the lookup ceases.
859 This feature is intended for use in master/slave situations where updates
860 are occurring, and one wants to update a master rather than a slave. If the
861 masters are in the list for reading, you might have:
863 mysql_servers = slave1/db/name/pw:slave2/db/name/pw:master/db/name/pw
865 In an updating lookup, you could then write
867 ${lookup mysql{servers=master; UPDATE ...}
869 If, on the other hand, the master is not to be used for reading lookups:
871 pgsql_servers = slave1/db/name/pw:slave2/db/name/pw
873 you can still update the master by
875 ${lookup pgsql{servers=master/db/name/pw; UPDATE ...}
877 11. The message_body_newlines option (default FALSE, for backwards
878 compatibility) can be used to control whether newlines are present in
879 $message_body and $message_body_end. If it is FALSE, they are replaced by
886 1. There is a new log selector called smtp_no_mail, which is not included in
887 the default setting. When it is set, a line is written to the main log
888 whenever an accepted SMTP connection terminates without having issued a
891 2. When an item in a dnslists list is followed by = and & and a list of IP
892 addresses, the behaviour was not clear when the lookup returned more than
893 one IP address. This has been solved by the addition of == and =& for "all"
894 rather than the default "any" matching.
896 3. Up till now, the only control over which cipher suites GnuTLS uses has been
897 for the cipher algorithms. New options have been added to allow some of the
898 other parameters to be varied.
900 4. There is a new compile-time option called ENABLE_DISABLE_FSYNC. When it is
901 set, Exim compiles a runtime option called disable_fsync.
903 5. There is a new variable called $smtp_count_at_connection_start.
905 6. There's a new control called no_pipelining.
907 7. There are two new variables called $sending_ip_address and $sending_port.
908 These are set whenever an SMTP connection to another host has been set up.
910 8. The expansion of the helo_data option in the smtp transport now happens
911 after the connection to the server has been made.
913 9. There is a new expansion operator ${rfc2047d: that decodes strings that
914 are encoded as per RFC 2047.
916 10. There is a new log selector called "pid", which causes the current process
917 id to be added to every log line, in square brackets, immediately after the
920 11. Exim has been modified so that it flushes SMTP output before implementing
921 a delay in an ACL. It also flushes the output before performing a callout,
922 as this can take a substantial time. These behaviours can be disabled by
923 obeying control = no_delay_flush or control = no_callout_flush,
924 respectively, at some earlier stage of the connection.
926 12. There are two new expansion conditions that iterate over a list. They are
927 called forany and forall.
929 13. There's a new global option called dsn_from that can be used to vary the
930 contents of From: lines in bounces and other automatically generated
931 messages ("delivery status notifications" - hence the name of the option).
933 14. The smtp transport has a new option called hosts_avoid_pipelining.
935 15. By default, exigrep does case-insensitive matches. There is now a -I option
936 that makes it case-sensitive.
938 16. A number of new features ("addresses", "map", "filter", and "reduce") have
939 been added to string expansions to make it easier to process lists of
940 items, typically addresses.
942 17. There's a new ACL modifier called "continue". It does nothing of itself,
943 and processing of the ACL always continues with the next condition or
944 modifier. It is provided so that the side effects of expanding its argument
947 18. It is now possible to use newline and other control characters (those with
948 values less than 32, plus DEL) as separators in lists.
950 19. The exigrep utility now has a -v option, which inverts the matching
953 20. The host_find_failed option in the manualroute router can now be set to
960 No new features were added to 4.66.
966 No new features were added to 4.65.
972 1. ACL variables can now be given arbitrary names, as long as they start with
973 "acl_c" or "acl_m" (for connection variables and message variables), are at
974 least six characters long, with the sixth character being either a digit or
977 2. There is a new ACL modifier called log_reject_target. It makes it possible
978 to specify which logs are used for messages about ACL rejections.
980 3. There is a new authenticator called "dovecot". This is an interface to the
981 authentication facility of the Dovecot POP/IMAP server, which can support a
982 number of authentication methods.
984 4. The variable $message_headers_raw provides a concatenation of all the
985 messages's headers without any decoding. This is in contrast to
986 $message_headers, which does RFC2047 decoding on the header contents.
988 5. In a DNS black list, if two domain names, comma-separated, are given, the
989 second is used first to do an initial check, making use of any IP value
990 restrictions that are set. If there is a match, the first domain is used,
991 without any IP value restrictions, to get the TXT record.
993 6. All authenticators now have a server_condition option.
995 7. There is a new command-line option called -Mset. It is useful only in
996 conjunction with -be (that is, when testing string expansions). It must be
997 followed by a message id; Exim loads the given message from its spool
998 before doing the expansions.
1000 8. Another similar new command-line option is called -bem. It operates like
1001 -be except that it must be followed by the name of a file that contains a
1004 9. When an address is delayed because of a 4xx response to a RCPT command, it
1005 is now the combination of sender and recipient that is delayed in
1006 subsequent queue runs until its retry time is reached.
1008 10. Unary negation and the bitwise logical operators and, or, xor, not, and
1009 shift, have been added to the eval: and eval10: expansion items.
1011 11. The variables $interface_address and $interface_port have been renamed
1012 as $received_ip_address and $received_port, to make it clear that they
1013 relate to message reception rather than delivery. (The old names remain
1014 available for compatibility.)
1016 12. The "message" modifier can now be used on "accept" and "discard" acl verbs
1017 to vary the message that is sent when an SMTP command is accepted.
1023 1. There is a new Boolean option called filter_prepend_home for the redirect
1026 2. There is a new acl, set by acl_not_smtp_start, which is run right at the
1027 start of receiving a non-SMTP message, before any of the message has been
1030 3. When an SMTP error message is specified in a "message" modifier in an ACL,
1031 or in a :fail: or :defer: message in a redirect router, Exim now checks the
1032 start of the message for an SMTP error code.
1034 4. There is a new parameter for LDAP lookups called "referrals", which takes
1035 one of the settings "follow" (the default) or "nofollow".
1037 5. Version 20070721.2 of exipick now included, offering these new options:
1039 After all other sorting options have bee processed, reverse order
1040 before displaying messages (-R is synonym).
1042 Randomize order of matching messages before displaying.
1044 Instead of displaying the matching messages, display the sum
1046 --sort <variable>[,<variable>...]
1047 Before displaying matching messages, sort the messages according to
1048 each messages value for each variable.
1050 Negate the value for every test (returns inverse output from the
1051 same criteria without --not).
1057 1. The ${readsocket expansion item now supports Internet domain sockets as well
1058 as Unix domain sockets. If the first argument begins "inet:", it must be of
1059 the form "inet:host:port". The port is mandatory; it may be a number or the
1060 name of a TCP port in /etc/services. The host may be a name, or it may be an
1061 IP address. An ip address may optionally be enclosed in square brackets.
1062 This is best for IPv6 addresses. For example:
1064 ${readsocket{inet:[::1]:1234}{<request data>}...
1066 Only a single host name may be given, but if looking it up yield more than
1067 one IP address, they are each tried in turn until a connection is made. Once
1068 a connection has been made, the behaviour is as for ${readsocket with a Unix
1071 2. If a redirect router sets up file or pipe deliveries for more than one
1072 incoming address, and the relevant transport has batch_max set greater than
1073 one, a batch delivery now occurs.
1075 3. The appendfile transport has a new option called maildirfolder_create_regex.
1076 Its value is a regular expression. For a maildir delivery, this is matched
1077 against the maildir directory; if it matches, Exim ensures that a
1078 maildirfolder file is created alongside the new, cur, and tmp directories.
1084 The documentation is up-to-date for the 4.61 release. Major new features since
1085 the 4.60 release are:
1087 . An option called disable_ipv6, to disable the use of IPv6 completely.
1089 . An increase in the number of ACL variables to 20 of each type.
1091 . A change to use $auth1, $auth2, and $auth3 in authenticators instead of $1,
1092 $2, $3, (though those are still set) because the numeric variables get used
1093 for other things in complicated expansions.
1095 . The default for rfc1413_query_timeout has been changed from 30s to 5s.
1097 . It is possible to use setclassresources() on some BSD OS to control the
1098 resources used in pipe deliveries.
1100 . A new ACL modifier called add_header, which can be used with any verb.
1102 . More errors are detectable in retry rules.
1104 There are a number of other additions too.
1110 The documentation is up-to-date for the 4.60 release. Major new features since
1111 the 4.50 release are:
1113 . Support for SQLite.
1115 . Support for IGNOREQUOTA in LMTP.
1117 . Extensions to the "submission mode" features.
1119 . Support for Client SMTP Authorization (CSA).
1121 . Support for ratelimiting hosts and users.
1123 . New expansion items to help with the BATV "prvs" scheme.
1125 . A "match_ip" condition, that matches an IP address against a list.
1127 There are many more minor changes.
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