4 This file contains descriptions of new features that have been added to Exim.
5 Before a formal release, there may be quite a lot of detail so that people can
6 test from the snapshots or the Git before the documentation is updated. Once
7 the documentation is updated, this file is reduced to a short list.
12 1. PKG_CONFIG_PATH can now be set in Local/Makefile;
13 wildcards will be expanded, values are collapsed.
15 2. The ${readsocket } expansion now takes an option to not shutdown the
16 connection after sending the query string. The default remains to do so.
18 3. An smtp transport option "hosts_noproxy_tls" to control whether multiple
19 deliveries on a single TCP connection can maintain a TLS connection
20 open. By default disabled for all hosts, doing so saves the cost of
21 making new TLS sessions, at the cost of having to proxy the data via
22 another process. Logging is also affected.
24 4. A malware connection type for the FPSCAND protocol.
26 5. An option for recipient verify callouts to hold the connection open for
27 further recipients and for delivery.
29 6. The reproducible build $SOURCE_DATE_EPOCH environment variable is now
32 7. Optionally, an alternate format for spool data-files which matches the
33 wire format - meaning more efficient reception and transmission (at the
34 cost of difficulty with standard Unix tools). Only used for messages
35 received using the ESMTP CHUNKING option, and when a new main-section
36 option "spool_wireformat" (false by default) is set.
38 8. New main configuration option "commandline_checks_require_admin" to
39 restrict who can use various introspection options.
45 1. Allow relative config file names for ".include"
47 2. A main-section config option "debug_store" to control the checks on
48 variable locations during store-reset. Normally false but can be enabled
49 when a memory corrution issue is suspected on a production system.
55 1. The new perl_taintmode option allows to run the embedded perl
56 interpreter in taint mode.
58 2. New log_selector: dnssec, adds a "DS" tag to acceptance and delivery lines.
60 3. Speculative debugging, via a "kill" option to the "control=debug" ACL
63 4. New expansion item ${sha3:<string>} / ${sha3_<N>:<string>}.
64 N can be 224, 256 (default), 384, 512.
65 With GnuTLS 3.5.0 or later, only.
67 5. Facility for named queues: A command-line argument can specify
68 the queue name for a queue operation, and an ACL modifier can set
69 the queue to be used for a message. A $queue_name variable gives
72 6. New expansion operators base32/base32d.
74 7. The CHUNKING ESMTP extension from RFC 3030. May give some slight
75 performance increase and network load decrease. Main config option
76 chunking_advertise_hosts, and smtp transport option hosts_try_chunking
79 8. LMDB lookup support, as Experimental. Patch supplied by Andrew Colin Kissa.
81 9. Expansion operator escape8bit, like escape but not touching newline etc..
83 10. Feature macros, generated from compile options. All start with "_HAVE_"
84 and go on with some roughly recognisable name. Driver macros, for
85 router, transport and authentication drivers; names starting with "_DRIVER_".
86 Option macros, for each configuration-file option; all start with "_OPT_".
87 Use the "-bP macros" command-line option to see what is present.
89 11. Integer values for options can take a "G" multiplier.
91 12. defer=pass option for the ACL control cutthrough_delivery, to reflect 4xx
92 returns from the target back to the initiator, rather than spooling the
95 13. New built-in constants available for tls_dhparam and default changed.
97 14. If built with EXPERIMENTAL_QUEUEFILE, a queuefile transport, for writing
98 out copies of the message spool files for use by 3rd-party scanners.
100 15. A new option on the smtp transport, hosts_try_fastopen. If the system
101 supports it (on Linux it must be enabled in the kernel by the sysadmin)
102 try to use RFC 7413 "TCP Fast Open". No data is sent on the SYN segment
103 but it permits a peer that also supports the facility to send its SMTP
104 banner immediately after the SYN,ACK segment rather then waiting for
105 another ACK - so saving up to one roundtrip time. Because it requires
106 previous communication with the peer (we save a cookie from it) this
107 will only become active on frequently-contacted destinations.
109 16. A new syslog_pid option to suppress PID duplication in syslog lines.
115 1. The ACL conditions regex and mime_regex now capture substrings
116 into numeric variables $regex1 to 9, like the "match" expansion condition.
118 2. New $callout_address variable records the address used for a spam=,
119 malware= or verify= callout.
121 3. Transports now take a "max_parallel" option, to limit concurrency.
123 4. Expansion operators ${ipv6norm:<string>} and ${ipv6denorm:<string>}.
124 The latter expands to a 8-element colon-sep set of hex digits including
125 leading zeroes. A trailing ipv4-style dotted-decimal set is converted
126 to hex. Pure ipv4 addresses are converted to IPv4-mapped IPv6.
127 The former operator strips leading zeroes and collapses the longest
128 set of 0-groups to a double-colon.
130 5. New "-bP config" support, to dump the effective configuration.
132 6. New $dkim_key_length variable.
134 7. New base64d and base64 expansion items (the existing str2b64 being a
135 synonym of the latter). Add support in base64 for certificates.
137 8. New main configuration option "bounce_return_linesize_limit" to
138 avoid oversize bodies in bounces. The default value matches RFC
141 9. New $initial_cwd expansion variable.
147 1. Support for using the system standard CA bundle.
149 2. New expansion items $config_file, $config_dir, containing the file
150 and directory name of the main configuration file. Also $exim_version.
152 3. New "malware=" support for Avast.
154 4. New "spam=" variant option for Rspamd.
156 5. Assorted options on malware= and spam= scanners.
158 6. A command-line option to write a comment into the logfile.
160 7. If built with EXPERIMENTAL_SOCKS feature enabled, the smtp transport can
161 be configured to make connections via socks5 proxies.
163 8. If built with EXPERIMENTAL_INTERNATIONAL, support is included for
164 the transmission of UTF-8 envelope addresses.
166 9. If built with EXPERIMENTAL_INTERNATIONAL, an expansion item for a commonly
167 used encoding of Maildir folder names.
169 10. A logging option for slow DNS lookups.
171 11. New ${env {<variable>}} expansion.
173 12. A non-SMTP authenticator using information from TLS client certificates.
175 13. Main option "tls_eccurve" for selecting an Elliptic Curve for TLS.
176 Patch originally by Wolfgang Breyha.
178 14. Main option "dns_trust_aa" for trusting your local nameserver at the
179 same level as DNSSEC.
185 1. If built with EXPERIMENTAL_DANE feature enabled, Exim will follow the
186 DANE SMTP draft to assess a secure chain of trust of the certificate
187 used to establish the TLS connection based on a TLSA record in the
188 domain of the sender.
190 2. The EXPERIMENTAL_TPDA feature has been renamed to EXPERIMENTAL_EVENT
191 and several new events have been created. The reason is because it has
192 been expanded beyond just firing events during the transport phase. Any
193 existing TPDA transport options will have to be rewritten to use a new
194 $event_name expansion variable in a condition. Refer to the
195 experimental-spec.txt for details and examples.
197 3. The EXPERIMENTAL_CERTNAMES features is an enhancement to verify that
198 server certs used for TLS match the result of the MX lookup. It does
199 not use the same mechanism as DANE.
209 1. If built with the EXPERIMENTAL_PROXY feature enabled, Exim can be
210 configured to expect an initial header from a proxy that will make the
211 actual external source IP:host be used in exim instead of the IP of the
212 proxy that is connecting to it.
214 2. New verify option header_names_ascii, which will check to make sure
215 there are no non-ASCII characters in header names. Exim itself handles
216 those non-ASCII characters, but downstream apps may not, so Exim can
217 detect and reject if those characters are present.
219 3. New expansion operator ${utf8clean:string} to replace malformed UTF8
220 codepoints with valid ones.
222 4. New malware type "sock". Talks over a Unix or TCP socket, sending one
223 command line and matching a regex against the return data for trigger
224 and a second regex to extract malware_name. The mail spoolfile name can
225 be included in the command line.
227 5. The smtp transport now supports options "tls_verify_hosts" and
228 "tls_try_verify_hosts". If either is set the certificate verification
229 is split from the encryption operation. The default remains that a failed
230 verification cancels the encryption.
232 6. New SERVERS override of default ldap server list. In the ACLs, an ldap
233 lookup can now set a list of servers to use that is different from the
236 7. New command-line option -C for exiqgrep to specify alternate exim.conf
237 file when searching the queue.
239 8. OCSP now supports GnuTLS also, if you have version 3.1.3 or later of that.
241 9. Support for DNSSEC on outbound connections.
243 10. New variables "tls_(in,out)_(our,peer)cert" and expansion item
244 "certextract" to extract fields from them. Hash operators md5 and sha1
245 work over them for generating fingerprints, and a new sha256 operator
248 11. PRDR is now supported dy default.
250 12. OCSP stapling is now supported by default.
252 13. If built with the EXPERIMENTAL_DSN feature enabled, Exim will output
253 Delivery Status Notification messages in MIME format, and negotiate
254 DSN features per RFC 3461.
260 1. New command-line option -bI:sieve will list all supported sieve extensions
261 of this Exim build on standard output, one per line.
262 ManageSieve (RFC 5804) providers managing scripts for use by Exim should
263 query this to establish the correct list to include in the protocol's
264 SIEVE capability line.
266 2. If the -n option is combined with the -bP option, then the name of an
267 emitted option is not output, only the value (if visible to you).
268 For instance, "exim -n -bP pid_file_path" should just emit a pathname
269 followed by a newline, and no other text.
271 3. When built with SUPPORT_TLS and USE_GNUTLS, the SMTP transport driver now
272 has a "tls_dh_min_bits" option, to set the minimum acceptable number of
273 bits in the Diffie-Hellman prime offered by a server (in DH ciphersuites)
274 acceptable for security. (Option accepted but ignored if using OpenSSL).
275 Defaults to 1024, the old value. May be lowered only to 512, or raised as
276 far as you like. Raising this may hinder TLS interoperability with other
277 sites and is not currently recommended. Lowering this will permit you to
278 establish a TLS session which is not as secure as you might like.
280 Unless you really know what you are doing, leave it alone.
282 4. If not built with DISABLE_DNSSEC, Exim now has the main option
283 dns_dnssec_ok; if set to 1 then Exim will initialise the resolver library
284 to send the DO flag to your recursive resolver. If you have a recursive
285 resolver, which can set the Authenticated Data (AD) flag in results, Exim
286 can now detect this. Exim does not perform validation itself, instead
287 relying upon a trusted path to the resolver.
289 Current status: work-in-progress; $sender_host_dnssec variable added.
291 5. DSCP support for outbound connections: on a transport using the smtp driver,
292 set "dscp = ef", for instance, to cause the connections to have the relevant
293 DSCP (IPv4 TOS or IPv6 TCLASS) value in the header.
295 Similarly for inbound connections, there is a new control modifier, dscp,
296 so "warn control = dscp/ef" in the connect ACL, or after authentication.
298 Supported values depend upon system libraries. "exim -bI:dscp" to list the
299 ones Exim knows of. You can also set a raw number 0..0x3F.
301 6. The -G command-line flag is no longer ignored; it is now equivalent to an
302 ACL setting "control = suppress_local_fixups". The -L command-line flag
303 is now accepted and forces use of syslog, with the provided tag as the
304 process name. A few other flags used by Sendmail are now accepted and
307 7. New cutthrough routing feature. Requested by a "control = cutthrough_delivery"
308 ACL modifier; works for single-recipient mails which are received on and
309 deliverable via SMTP. Using the connection made for a recipient verify,
310 if requested before the verify, or a new one made for the purpose while
311 the inbound connection is still active. The bulk of the mail item is copied
312 direct from the inbound socket to the outbound (as well as the spool file).
313 When the source notifies the end of data, the data acceptance by the destination
314 is negotiated before the acceptance is sent to the source. If the destination
315 does not accept the mail item, for example due to content-scanning, the item
316 is not accepted from the source and therefore there is no need to generate
317 a bounce mail. This is of benefit when providing a secondary-MX service.
318 The downside is that delays are under the control of the ultimate destination
321 The Received-by: header on items delivered by cutthrough is generated
322 early in reception rather than at the end; this will affect any timestamp
323 included. The log line showing delivery is recorded before that showing
324 reception; it uses a new ">>" tag instead of "=>".
326 To support the feature, verify-callout connections can now use ESMTP and TLS.
327 The usual smtp transport options are honoured, plus a (new, default everything)
328 hosts_verify_avoid_tls.
330 New variable families named tls_in_cipher, tls_out_cipher etc. are introduced
331 for specific access to the information for each connection. The old names
332 are present for now but deprecated.
334 Not yet supported: IGNOREQUOTA, SIZE, PIPELINING.
336 8. New expansion operators ${listnamed:name} to get the content of a named list
337 and ${listcount:string} to count the items in a list.
339 9. New global option "gnutls_allow_auto_pkcs11", defaults false. The GnuTLS
340 rewrite in 4.80 combines with GnuTLS 2.12.0 or later, to autoload PKCS11
341 modules. For some situations this is desirable, but we expect admin in
342 those situations to know they want the feature. More commonly, it means
343 that GUI user modules get loaded and are broken by the setuid Exim being
344 unable to access files specified in environment variables and passed
345 through, thus breakage. So we explicitly inhibit the PKCS11 initialisation
346 unless this new option is set.
348 Some older OS's with earlier versions of GnuTLS might not have pkcs11 ability,
349 so have also added a build option which can be used to build Exim with GnuTLS
350 but without trying to use any kind of PKCS11 support. Uncomment this in the
353 AVOID_GNUTLS_PKCS11=yes
355 10. The "acl = name" condition on an ACL now supports optional arguments.
356 New expansion item "${acl {name}{arg}...}" and expansion condition
357 "acl {{name}{arg}...}" are added. In all cases up to nine arguments
358 can be used, appearing in $acl_arg1 to $acl_arg9 for the called ACL.
359 Variable $acl_narg contains the number of arguments. If the ACL sets
360 a "message =" value this becomes the result of the expansion item,
361 or the value of $value for the expansion condition. If the ACL returns
362 accept the expansion condition is true; if reject, false. A defer
363 return results in a forced fail.
365 11. Routers and transports can now have multiple headers_add and headers_remove
366 option lines. The concatenated list is used.
368 12. New ACL modifier "remove_header" can remove headers before message gets
369 handled by routers/transports.
371 13. New dnsdb lookup pseudo-type "a+". A sequence of "a6" (if configured),
372 "aaaa" and "a" lookups is done and the full set of results returned.
374 14. New expansion variable $headers_added with content from ACL add_header
375 modifier (but not yet added to message).
377 15. New 8bitmime status logging option for received messages. Log field "M8S".
379 16. New authenticated_sender logging option, adding to log field "A".
381 17. New expansion variables $router_name and $transport_name. Useful
382 particularly for debug_print as -bt command-line option does not
383 require privilege whereas -d does.
385 18. If built with EXPERIMENTAL_PRDR, per-recipient data responses per a
386 proposed extension to SMTP from Eric Hall.
388 19. The pipe transport has gained the force_command option, to allow
389 decorating commands from user .forward pipe aliases with prefix
390 wrappers, for instance.
392 20. Callout connections can now AUTH; the same controls as normal delivery
395 21. Support for DMARC, using opendmarc libs, can be enabled. It adds new
396 options: dmarc_forensic_sender, dmarc_history_file, and dmarc_tld_file.
397 It adds new expansion variables $dmarc_ar_header, $dmarc_status,
398 $dmarc_status_text, and $dmarc_used_domain. It adds a new acl modifier
399 dmarc_status. It adds new control flags dmarc_disable_verify and
400 dmarc_enable_forensic.
402 22. Add expansion variable $authenticated_fail_id, which is the username
403 provided to the authentication method which failed. It is available
404 for use in subsequent ACL processing (typically quit or notquit ACLs).
406 23. New ACL modifier "udpsend" can construct a UDP packet to send to a given
409 24. New ${hexquote:..string..} expansion operator converts non-printable
410 characters in the string to \xNN form.
412 25. Experimental TPDA (Transport Post Delivery Action) function added.
413 Patch provided by Axel Rau.
415 26. Experimental Redis lookup added. Patch provided by Warren Baker.
421 1. New authenticator driver, "gsasl". Server-only (at present).
422 This is a SASL interface, licensed under GPL, which can be found at
423 http://www.gnu.org/software/gsasl/.
424 This system does not provide sources of data for authentication, so
425 careful use needs to be made of the conditions in Exim.
427 2. New authenticator driver, "heimdal_gssapi". Server-only.
428 A replacement for using cyrus_sasl with Heimdal, now that $KRB5_KTNAME
429 is no longer honoured for setuid programs by Heimdal. Use the
430 "server_keytab" option to point to the keytab.
432 3. The "pkg-config" system can now be used when building Exim to reference
433 cflags and library information for lookups and authenticators, rather
434 than having to update "CFLAGS", "AUTH_LIBS", "LOOKUP_INCLUDE" and
435 "LOOKUP_LIBS" directly. Similarly for handling the TLS library support
436 without adjusting "TLS_INCLUDE" and "TLS_LIBS".
438 In addition, setting PCRE_CONFIG=yes will query the pcre-config tool to
439 find the headers and libraries for PCRE.
441 4. New expansion variable $tls_bits.
443 5. New lookup type, "dbmjz". Key is an Exim list, the elements of which will
444 be joined together with ASCII NUL characters to construct the key to pass
445 into the DBM library. Can be used with gsasl to access sasldb2 files as
448 6. OpenSSL now supports TLS1.1 and TLS1.2 with OpenSSL 1.0.1.
450 Avoid release 1.0.1a if you can. Note that the default value of
451 "openssl_options" is no longer "+dont_insert_empty_fragments", as that
452 increased susceptibility to attack. This may still have interoperability
453 implications for very old clients (see version 4.31 change 37) but
454 administrators can choose to make the trade-off themselves and restore
455 compatibility at the cost of session security.
457 7. Use of the new expansion variable $tls_sni in the main configuration option
458 tls_certificate will cause Exim to re-expand the option, if the client
459 sends the TLS Server Name Indication extension, to permit choosing a
460 different certificate; tls_privatekey will also be re-expanded. You must
461 still set these options to expand to valid files when $tls_sni is not set.
463 The SMTP Transport has gained the option tls_sni, which will set a hostname
464 for outbound TLS sessions, and set $tls_sni too.
466 A new log_selector, +tls_sni, has been added, to log received SNI values
467 for Exim as a server.
469 8. The existing "accept_8bitmime" option now defaults to true. This means
470 that Exim is deliberately not strictly RFC compliant. We're following
471 Dan Bernstein's advice in http://cr.yp.to/smtp/8bitmime.html by default.
472 Those who disagree, or know that they are talking to mail servers that,
473 even today, are not 8-bit clean, need to turn off this option.
475 9. Exim can now be started with -bw (with an optional timeout, given as
476 -bw<timespec>). With this, stdin at startup is a socket that is
477 already listening for connections. This has a more modern name of
478 "socket activation", but forcing the activated socket to fd 0. We're
479 interested in adding more support for modern variants.
481 10. ${eval } now uses 64-bit values on supporting platforms. A new "G" suffix
482 for numbers indicates multiplication by 1024^3.
484 11. The GnuTLS support has been revamped; the three options gnutls_require_kx,
485 gnutls_require_mac & gnutls_require_protocols are no longer supported.
486 tls_require_ciphers is now parsed by gnutls_priority_init(3) as a priority
487 string, documentation for which is at:
488 http://www.gnutls.org/manual/html_node/Priority-Strings.html
490 SNI support has been added to Exim's GnuTLS integration too.
492 For sufficiently recent GnuTLS libraries, ${randint:..} will now use
493 gnutls_rnd(), asking for GNUTLS_RND_NONCE level randomness.
495 12. With OpenSSL, if built with EXPERIMENTAL_OCSP, a new option tls_ocsp_file
496 is now available. If the contents of the file are valid, then Exim will
497 send that back in response to a TLS status request; this is OCSP Stapling.
498 Exim will not maintain the contents of the file in any way: administrators
499 are responsible for ensuring that it is up-to-date.
501 See "experimental-spec.txt" for more details.
503 13. ${lookup dnsdb{ }} supports now SPF record types. They are handled
504 identically to TXT record lookups.
506 14. New expansion variable $tod_epoch_l for higher-precision time.
508 15. New global option tls_dh_max_bits, defaulting to current value of NSS
509 hard-coded limit of DH ephemeral bits, to fix interop problems caused by
510 GnuTLS 2.12 library recommending a bit count higher than NSS supports.
512 16. tls_dhparam now used by both OpenSSL and GnuTLS, can be path or identifier.
513 Option can now be a path or an identifier for a standard prime.
514 If unset, we use the DH prime from section 2.2 of RFC 5114, "ike23".
515 Set to "historic" to get the old GnuTLS behaviour of auto-generated DH
518 17. SSLv2 now disabled by default in OpenSSL. (Never supported by GnuTLS).
519 Use "openssl_options -no_sslv2" to re-enable support, if your OpenSSL
520 install was not built with OPENSSL_NO_SSL2 ("no-ssl2").
526 1. New options for the ratelimit ACL condition: /count= and /unique=.
527 The /noupdate option has been replaced by a /readonly option.
529 2. The SMTP transport's protocol option may now be set to "smtps", to
530 use SSL-on-connect outbound.
532 3. New variable $av_failed, set true if the AV scanner deferred; ie, when
533 there is a problem talking to the AV scanner, or the AV scanner running.
535 4. New expansion conditions, "inlist" and "inlisti", which take simple lists
536 and check if the search item is a member of the list. This does not
537 support named lists, but does subject the list part to string expansion.
539 5. Unless the new EXPAND_LISTMATCH_RHS build option is set when Exim was
540 built, Exim no longer performs string expansion on the second string of
541 the match_* expansion conditions: "match_address", "match_domain",
542 "match_ip" & "match_local_part". Named lists can still be used.
548 1. The global option "dns_use_edns0" may be set to coerce EDNS0 usage on
549 or off in the resolver library.
555 1. In addition to the existing LDAP and LDAP/SSL ("ldaps") support, there
556 is now LDAP/TLS support, given sufficiently modern OpenLDAP client
557 libraries. The following global options have been added in support of
558 this: ldap_ca_cert_dir, ldap_ca_cert_file, ldap_cert_file, ldap_cert_key,
559 ldap_cipher_suite, ldap_require_cert, ldap_start_tls.
561 2. The pipe transport now takes a boolean option, "freeze_signal", default
562 false. When true, if the external delivery command exits on a signal then
563 Exim will freeze the message in the queue, instead of generating a bounce.
565 3. Log filenames may now use %M as an escape, instead of %D (still available).
566 The %M pattern expands to yyyymm, providing month-level resolution.
568 4. The $message_linecount variable is now updated for the maildir_tag option,
569 in the same way as $message_size, to reflect the real number of lines,
570 including any header additions or removals from transport.
572 5. When contacting a pool of SpamAssassin servers configured in spamd_address,
573 Exim now selects entries randomly, to better scale in a cluster setup.
579 1. SECURITY FIX: privilege escalation flaw fixed. On Linux (and only Linux)
580 the flaw permitted the Exim run-time user to cause root to append to
581 arbitrary files of the attacker's choosing, with the content based
582 on content supplied by the attacker.
584 2. Exim now supports loading some lookup types at run-time, using your
585 platform's dlopen() functionality. This has limited platform support
586 and the intention is not to support every variant, it's limited to
587 dlopen(). This permits the main Exim binary to not be linked against
588 all the libraries needed for all the lookup types.
594 NOTE: this version is not guaranteed backwards-compatible, please read the
595 items below carefully
597 1. A new main configuration option, "openssl_options", is available if Exim
598 is built with SSL support provided by OpenSSL. The option allows
599 administrators to specify OpenSSL options to be used on connections;
600 typically this is to set bug compatibility features which the OpenSSL
601 developers have not enabled by default. There may be security
602 consequences for certain options, so these should not be changed
605 2. A new pipe transport option, "permit_coredumps", may help with problem
606 diagnosis in some scenarios. Note that Exim is typically installed as
607 a setuid binary, which on most OSes will inhibit coredumps by default,
608 so that safety mechanism would have to be overridden for this option to
609 be able to take effect.
611 3. ClamAV 0.95 is now required for ClamAV support in Exim, unless
612 Local/Makefile sets: WITH_OLD_CLAMAV_STREAM=yes
613 Note that this switches Exim to use a new API ("INSTREAM") and a future
614 release of ClamAV will remove support for the old API ("STREAM").
616 The av_scanner option, when set to "clamd", now takes an optional third
617 part, "local", which causes Exim to pass a filename to ClamAV instead of
618 the file content. This is the same behaviour as when clamd is pointed at
619 a Unix-domain socket. For example:
621 av_scanner = clamd:192.0.2.3 1234:local
623 ClamAV's ExtendedDetectionInfo response format is now handled.
625 4. There is now a -bmalware option, restricted to admin users. This option
626 takes one parameter, a filename, and scans that file with Exim's
627 malware-scanning framework. This is intended purely as a debugging aid
628 to ensure that Exim's scanning is working, not to replace other tools.
629 Note that the ACL framework is not invoked, so if av_scanner references
630 ACL variables without a fallback then this will fail.
632 5. There is a new expansion operator, "reverse_ip", which will reverse IP
633 addresses; IPv4 into dotted quad, IPv6 into dotted nibble. Examples:
635 ${reverse_ip:192.0.2.4}
637 ${reverse_ip:2001:0db8:c42:9:1:abcd:192.0.2.3}
638 -> 3.0.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2
640 6. There is a new ACL control called "debug", to enable debug logging.
641 This allows selective logging of certain incoming transactions within
642 production environments, with some care. It takes two options, "tag"
643 and "opts"; "tag" is included in the filename of the log and "opts"
644 is used as per the -d<options> command-line option. Examples, which
645 don't all make sense in all contexts:
648 control = debug/tag=.$sender_host_address
649 control = debug/opts=+expand+acl
650 control = debug/tag=.$message_exim_id/opts=+expand
652 7. It has always been implicit in the design and the documentation that
653 "the Exim user" is not root. src/EDITME said that using root was
654 "very strongly discouraged". This is not enough to keep people from
655 shooting themselves in the foot in days when many don't configure Exim
656 themselves but via package build managers. The security consequences of
657 running various bits of network code are severe if there should be bugs in
658 them. As such, the Exim user may no longer be root. If configured
659 statically, Exim will refuse to build. If configured as ref:user then Exim
660 will exit shortly after start-up. If you must shoot yourself in the foot,
661 then henceforth you will have to maintain your own local patches to strip
664 8. There is a new expansion condition, bool_lax{}. Where bool{} uses the ACL
665 condition logic to determine truth/failure and will fail to expand many
666 strings, bool_lax{} uses the router condition logic, where most strings
668 Note: bool{00} is false, bool_lax{00} is true.
670 9. Routers now support multiple "condition" tests.
672 10. There is now a runtime configuration option "tcp_wrappers_daemon_name".
673 Setting this allows an admin to define which entry in the tcpwrappers
674 config file will be used to control access to the daemon. This option
675 is only available when Exim is built with USE_TCP_WRAPPERS. The
676 default value is set at build time using the TCP_WRAPPERS_DAEMON_NAME
679 11. [POSSIBLE CONFIG BREAKAGE] The default value for system_filter_user is now
680 the Exim run-time user, instead of root.
682 12. [POSSIBLE CONFIG BREAKAGE] ALT_CONFIG_ROOT_ONLY is no longer optional and
683 is forced on. This is mitigated by the new build option
684 TRUSTED_CONFIG_LIST which defines a list of configuration files which
685 are trusted; one per line. If a config file is owned by root and matches
686 a pathname in the list, then it may be invoked by the Exim build-time
687 user without Exim relinquishing root privileges.
689 13. [POSSIBLE CONFIG BREAKAGE] The Exim user is no longer automatically
690 trusted to supply -D<Macro[=Value]> overrides on the command-line. Going
691 forward, we recommend using TRUSTED_CONFIG_LIST with shim configs that
692 include the main config. As a transition mechanism, we are temporarily
693 providing a work-around: the new build option WHITELIST_D_MACROS provides
694 a colon-separated list of macro names which may be overridden by the Exim
695 run-time user. The values of these macros are constrained to the regex
696 ^[A-Za-z0-9_/.-]*$ (which explicitly does allow for empty values).
702 1. TWO SECURITY FIXES: one relating to mail-spools which are globally
703 writable, the other to locking of MBX folders (not mbox).
705 2. MySQL stored procedures are now supported.
707 3. The dkim_domain transport option is now a list, not a single string, and
708 messages will be signed for each element in the list (discarding
711 4. The 4.70 release unexpectedly changed the behaviour of dnsdb TXT lookups
712 in the presence of multiple character strings within the RR. Prior to 4.70,
713 only the first string would be returned. The dnsdb lookup now, by default,
714 preserves the pre-4.70 semantics, but also now takes an extended output
715 separator specification. The separator can be followed by a semicolon, to
716 concatenate the individual text strings together with no join character,
717 or by a comma and a second separator character, in which case the text
718 strings within a TXT record are joined on that second character.
719 Administrators are reminded that DNS provides no ordering guarantees
720 between multiple records in an RRset. For example:
722 foo.example. IN TXT "a" "b" "c"
723 foo.example. IN TXT "d" "e" "f"
725 ${lookup dnsdb{>/ txt=foo.example}} -> "a/d"
726 ${lookup dnsdb{>/; txt=foo.example}} -> "def/abc"
727 ${lookup dnsdb{>/,+ txt=foo.example}} -> "a+b+c/d+e+f"
733 1. Native DKIM support without an external library.
734 (Note that if no action to prevent it is taken, a straight upgrade will
735 result in DKIM verification of all signed incoming emails. See spec
736 for details on conditionally disabling)
738 2. Experimental DCC support via dccifd (contributed by Wolfgang Breyha).
740 3. There is now a bool{} expansion condition which maps certain strings to
741 true/false condition values (most likely of use in conjunction with the
742 and{} expansion operator).
744 4. The $spam_score, $spam_bar and $spam_report variables are now available
747 5. exim -bP now supports "macros", "macro_list" or "macro MACRO_NAME" as
748 options, provided that Exim is invoked by an admin_user.
750 6. There is a new option gnutls_compat_mode, when linked against GnuTLS,
751 which increases compatibility with older clients at the cost of decreased
752 security. Don't set this unless you need to support such clients.
754 7. There is a new expansion operator, ${randint:...} which will produce a
755 "random" number less than the supplied integer. This randomness is
756 not guaranteed to be cryptographically strong, but depending upon how
757 Exim was built may be better than the most naive schemes.
759 8. Exim now explicitly ensures that SHA256 is available when linked against
762 9. The transport_filter_timeout option now applies to SMTP transports too.
768 1. Preliminary DKIM support in Experimental.
774 1. The body_linecount and body_zerocount C variables are now exported in the
777 2. When a dnslists lookup succeeds, the key that was looked up is now placed
778 in $dnslist_matched. When the key is an IP address, it is not reversed in
779 this variable (though it is, of course, in the actual lookup). In simple
782 deny dnslists = spamhaus.example
784 the key is also available in another variable (in this case,
785 $sender_host_address). In more complicated cases, however, this is not
786 true. For example, using a data lookup might generate a dnslists lookup
789 deny dnslists = spamhaus.example/<|192.168.1.2|192.168.6.7|...
791 If this condition succeeds, the value in $dnslist_matched might be
792 192.168.6.7 (for example).
794 3. Authenticators now have a client_condition option. When Exim is running as
795 a client, it skips an authenticator whose client_condition expansion yields
796 "0", "no", or "false". This can be used, for example, to skip plain text
797 authenticators when the connection is not encrypted by a setting such as:
799 client_condition = ${if !eq{$tls_cipher}{}}
801 Note that the 4.67 documentation states that $tls_cipher contains the
802 cipher used for incoming messages. In fact, during SMTP delivery, it
803 contains the cipher used for the delivery. The same is true for
806 4. There is now a -Mvc <message-id> option, which outputs a copy of the
807 message to the standard output, in RFC 2822 format. The option can be used
808 only by an admin user.
810 5. There is now a /noupdate option for the ratelimit ACL condition. It
811 computes the rate and checks the limit as normal, but it does not update
812 the saved data. This means that, in relevant ACLs, it is possible to lookup
813 the existence of a specified (or auto-generated) ratelimit key without
814 incrementing the ratelimit counter for that key.
816 In order for this to be useful, another ACL entry must set the rate
817 for the same key somewhere (otherwise it will always be zero).
822 # Read the rate; if it doesn't exist or is below the maximum
824 deny ratelimit = 100 / 5m / strict / noupdate
825 log_message = RATE: $sender_rate / $sender_rate_period \
826 (max $sender_rate_limit)
828 [... some other logic and tests...]
830 warn ratelimit = 100 / 5m / strict / per_cmd
831 log_message = RATE UPDATE: $sender_rate / $sender_rate_period \
832 (max $sender_rate_limit)
833 condition = ${if le{$sender_rate}{$sender_rate_limit}}
837 6. The variable $max_received_linelength contains the number of bytes in the
838 longest line that was received as part of the message, not counting the
839 line termination character(s).
841 7. Host lists can now include +ignore_defer and +include_defer, analagous to
842 +ignore_unknown and +include_unknown. These options should be used with
843 care, probably only in non-critical host lists such as whitelists.
845 8. There's a new option called queue_only_load_latch, which defaults true.
846 If set false when queue_only_load is greater than zero, Exim re-evaluates
847 the load for each incoming message in an SMTP session. Otherwise, once one
848 message is queued, the remainder are also.
850 9. There is a new ACL, specified by acl_smtp_notquit, which is run in most
851 cases when an SMTP session ends without sending QUIT. However, when Exim
852 itself is is bad trouble, such as being unable to write to its log files,
853 this ACL is not run, because it might try to do things (such as write to
854 log files) that make the situation even worse.
856 Like the QUIT ACL, this new ACL is provided to make it possible to gather
857 statistics. Whatever it returns (accept or deny) is immaterial. The "delay"
858 modifier is forbidden in this ACL.
860 When the NOTQUIT ACL is running, the variable $smtp_notquit_reason is set
861 to a string that indicates the reason for the termination of the SMTP
862 connection. The possible values are:
864 acl-drop Another ACL issued a "drop" command
865 bad-commands Too many unknown or non-mail commands
866 command-timeout Timeout while reading SMTP commands
867 connection-lost The SMTP connection has been lost
868 data-timeout Timeout while reading message data
869 local-scan-error The local_scan() function crashed
870 local-scan-timeout The local_scan() function timed out
871 signal-exit SIGTERM or SIGINT
872 synchronization-error SMTP synchronization error
873 tls-failed TLS failed to start
875 In most cases when an SMTP connection is closed without having received
876 QUIT, Exim sends an SMTP response message before actually closing the
877 connection. With the exception of acl-drop, the default message can be
878 overridden by the "message" modifier in the NOTQUIT ACL. In the case of a
879 "drop" verb in another ACL, it is the message from the other ACL that is
882 10. For MySQL and PostgreSQL lookups, it is now possible to specify a list of
883 servers with individual queries. This is done by starting the query with
884 "servers=x:y:z;", where each item in the list may take one of two forms:
886 (1) If it is just a host name, the appropriate global option (mysql_servers
887 or pgsql_servers) is searched for a host of the same name, and the
888 remaining parameters (database, user, password) are taken from there.
890 (2) If it contains any slashes, it is taken as a complete parameter set.
892 The list of servers is used in exactly the same was as the global list.
893 Once a connection to a server has happened and a query has been
894 successfully executed, processing of the lookup ceases.
896 This feature is intended for use in master/slave situations where updates
897 are occurring, and one wants to update a master rather than a slave. If the
898 masters are in the list for reading, you might have:
900 mysql_servers = slave1/db/name/pw:slave2/db/name/pw:master/db/name/pw
902 In an updating lookup, you could then write
904 ${lookup mysql{servers=master; UPDATE ...}
906 If, on the other hand, the master is not to be used for reading lookups:
908 pgsql_servers = slave1/db/name/pw:slave2/db/name/pw
910 you can still update the master by
912 ${lookup pgsql{servers=master/db/name/pw; UPDATE ...}
914 11. The message_body_newlines option (default FALSE, for backwards
915 compatibility) can be used to control whether newlines are present in
916 $message_body and $message_body_end. If it is FALSE, they are replaced by
923 1. There is a new log selector called smtp_no_mail, which is not included in
924 the default setting. When it is set, a line is written to the main log
925 whenever an accepted SMTP connection terminates without having issued a
928 2. When an item in a dnslists list is followed by = and & and a list of IP
929 addresses, the behaviour was not clear when the lookup returned more than
930 one IP address. This has been solved by the addition of == and =& for "all"
931 rather than the default "any" matching.
933 3. Up till now, the only control over which cipher suites GnuTLS uses has been
934 for the cipher algorithms. New options have been added to allow some of the
935 other parameters to be varied.
937 4. There is a new compile-time option called ENABLE_DISABLE_FSYNC. When it is
938 set, Exim compiles a runtime option called disable_fsync.
940 5. There is a new variable called $smtp_count_at_connection_start.
942 6. There's a new control called no_pipelining.
944 7. There are two new variables called $sending_ip_address and $sending_port.
945 These are set whenever an SMTP connection to another host has been set up.
947 8. The expansion of the helo_data option in the smtp transport now happens
948 after the connection to the server has been made.
950 9. There is a new expansion operator ${rfc2047d: that decodes strings that
951 are encoded as per RFC 2047.
953 10. There is a new log selector called "pid", which causes the current process
954 id to be added to every log line, in square brackets, immediately after the
957 11. Exim has been modified so that it flushes SMTP output before implementing
958 a delay in an ACL. It also flushes the output before performing a callout,
959 as this can take a substantial time. These behaviours can be disabled by
960 obeying control = no_delay_flush or control = no_callout_flush,
961 respectively, at some earlier stage of the connection.
963 12. There are two new expansion conditions that iterate over a list. They are
964 called forany and forall.
966 13. There's a new global option called dsn_from that can be used to vary the
967 contents of From: lines in bounces and other automatically generated
968 messages ("delivery status notifications" - hence the name of the option).
970 14. The smtp transport has a new option called hosts_avoid_pipelining.
972 15. By default, exigrep does case-insensitive matches. There is now a -I option
973 that makes it case-sensitive.
975 16. A number of new features ("addresses", "map", "filter", and "reduce") have
976 been added to string expansions to make it easier to process lists of
977 items, typically addresses.
979 17. There's a new ACL modifier called "continue". It does nothing of itself,
980 and processing of the ACL always continues with the next condition or
981 modifier. It is provided so that the side effects of expanding its argument
984 18. It is now possible to use newline and other control characters (those with
985 values less than 32, plus DEL) as separators in lists.
987 19. The exigrep utility now has a -v option, which inverts the matching
990 20. The host_find_failed option in the manualroute router can now be set to
997 No new features were added to 4.66.
1003 No new features were added to 4.65.
1009 1. ACL variables can now be given arbitrary names, as long as they start with
1010 "acl_c" or "acl_m" (for connection variables and message variables), are at
1011 least six characters long, with the sixth character being either a digit or
1014 2. There is a new ACL modifier called log_reject_target. It makes it possible
1015 to specify which logs are used for messages about ACL rejections.
1017 3. There is a new authenticator called "dovecot". This is an interface to the
1018 authentication facility of the Dovecot POP/IMAP server, which can support a
1019 number of authentication methods.
1021 4. The variable $message_headers_raw provides a concatenation of all the
1022 messages's headers without any decoding. This is in contrast to
1023 $message_headers, which does RFC2047 decoding on the header contents.
1025 5. In a DNS black list, if two domain names, comma-separated, are given, the
1026 second is used first to do an initial check, making use of any IP value
1027 restrictions that are set. If there is a match, the first domain is used,
1028 without any IP value restrictions, to get the TXT record.
1030 6. All authenticators now have a server_condition option.
1032 7. There is a new command-line option called -Mset. It is useful only in
1033 conjunction with -be (that is, when testing string expansions). It must be
1034 followed by a message id; Exim loads the given message from its spool
1035 before doing the expansions.
1037 8. Another similar new command-line option is called -bem. It operates like
1038 -be except that it must be followed by the name of a file that contains a
1041 9. When an address is delayed because of a 4xx response to a RCPT command, it
1042 is now the combination of sender and recipient that is delayed in
1043 subsequent queue runs until its retry time is reached.
1045 10. Unary negation and the bitwise logical operators and, or, xor, not, and
1046 shift, have been added to the eval: and eval10: expansion items.
1048 11. The variables $interface_address and $interface_port have been renamed
1049 as $received_ip_address and $received_port, to make it clear that they
1050 relate to message reception rather than delivery. (The old names remain
1051 available for compatibility.)
1053 12. The "message" modifier can now be used on "accept" and "discard" acl verbs
1054 to vary the message that is sent when an SMTP command is accepted.
1060 1. There is a new Boolean option called filter_prepend_home for the redirect
1063 2. There is a new acl, set by acl_not_smtp_start, which is run right at the
1064 start of receiving a non-SMTP message, before any of the message has been
1067 3. When an SMTP error message is specified in a "message" modifier in an ACL,
1068 or in a :fail: or :defer: message in a redirect router, Exim now checks the
1069 start of the message for an SMTP error code.
1071 4. There is a new parameter for LDAP lookups called "referrals", which takes
1072 one of the settings "follow" (the default) or "nofollow".
1074 5. Version 20070721.2 of exipick now included, offering these new options:
1076 After all other sorting options have bee processed, reverse order
1077 before displaying messages (-R is synonym).
1079 Randomize order of matching messages before displaying.
1081 Instead of displaying the matching messages, display the sum
1083 --sort <variable>[,<variable>...]
1084 Before displaying matching messages, sort the messages according to
1085 each messages value for each variable.
1087 Negate the value for every test (returns inverse output from the
1088 same criteria without --not).
1094 1. The ${readsocket expansion item now supports Internet domain sockets as well
1095 as Unix domain sockets. If the first argument begins "inet:", it must be of
1096 the form "inet:host:port". The port is mandatory; it may be a number or the
1097 name of a TCP port in /etc/services. The host may be a name, or it may be an
1098 IP address. An ip address may optionally be enclosed in square brackets.
1099 This is best for IPv6 addresses. For example:
1101 ${readsocket{inet:[::1]:1234}{<request data>}...
1103 Only a single host name may be given, but if looking it up yield more than
1104 one IP address, they are each tried in turn until a connection is made. Once
1105 a connection has been made, the behaviour is as for ${readsocket with a Unix
1108 2. If a redirect router sets up file or pipe deliveries for more than one
1109 incoming address, and the relevant transport has batch_max set greater than
1110 one, a batch delivery now occurs.
1112 3. The appendfile transport has a new option called maildirfolder_create_regex.
1113 Its value is a regular expression. For a maildir delivery, this is matched
1114 against the maildir directory; if it matches, Exim ensures that a
1115 maildirfolder file is created alongside the new, cur, and tmp directories.
1121 The documentation is up-to-date for the 4.61 release. Major new features since
1122 the 4.60 release are:
1124 . An option called disable_ipv6, to disable the use of IPv6 completely.
1126 . An increase in the number of ACL variables to 20 of each type.
1128 . A change to use $auth1, $auth2, and $auth3 in authenticators instead of $1,
1129 $2, $3, (though those are still set) because the numeric variables get used
1130 for other things in complicated expansions.
1132 . The default for rfc1413_query_timeout has been changed from 30s to 5s.
1134 . It is possible to use setclassresources() on some BSD OS to control the
1135 resources used in pipe deliveries.
1137 . A new ACL modifier called add_header, which can be used with any verb.
1139 . More errors are detectable in retry rules.
1141 There are a number of other additions too.
1147 The documentation is up-to-date for the 4.60 release. Major new features since
1148 the 4.50 release are:
1150 . Support for SQLite.
1152 . Support for IGNOREQUOTA in LMTP.
1154 . Extensions to the "submission mode" features.
1156 . Support for Client SMTP Authorization (CSA).
1158 . Support for ratelimiting hosts and users.
1160 . New expansion items to help with the BATV "prvs" scheme.
1162 . A "match_ip" condition, that matches an IP address against a list.
1164 There are many more minor changes.
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