4 This file contains descriptions of new features that have been added to Exim.
5 Before a formal release, there may be quite a lot of detail so that people can
6 test from the snapshots or the Git before the documentation is updated. Once
7 the documentation is updated, this file is reduced to a short list.
12 1. Dual-certificate stacks on servers now support OCSP stapling, under GnuTLS
13 version 3.5.6 or later.
15 2. DANE is now supported under GnuTLS version 3.0.0 or later. Both GnuTLS and
16 OpenSSL versions are moved to mainline support from Experimental.
17 New SMTP transport option "dane_require_tls_ciphers".
19 3. Feature macros for the compiled-in set of malware scanner interfaces.
21 4. SPF support is promoted from Experimental to mainline status. The template
22 src/EDITME makefile does not enable its inclusion.
24 5. Logging control for DKIM verification. The existing DKIM log line is
25 controlled by a "dkim_verbose" selector which is _not_ enabled by default.
26 A new tag "DKIM=<domain>" is added to <= lines by default, controlled by
27 a "dkim" log_selector.
29 6. Receive duration on <= lines, under a new log_selector "receive_time".
31 7. Options "ipv4_only" and "ipv4_prefer" on the dnslookup router and on
32 routing rules in the manualroute router.
34 8. Expansion item ${sha3:<string>} / ${sha3_<N>:<string>} now also supported
35 under OpenSSL version 1.1.1 or later.
37 9. DKIM operations can now use the Ed25519 algorithm in addition to RSA, under
38 GnuTLS 3.6.0 or later.
40 10. Builtin feature-macros _CRYPTO_HASH_SHA3 and _CRYPTO_SIGN_ED25519, library
43 11. "exim -bP macro <name>" returns caller-usable status.
45 12. Expansion item ${authresults {<machine>}} for creating an
46 Authentication-Results: header.
48 13. EXPERIMENTAL_ARC. See the experimental.spec file.
50 14: A dane:fail event, intended to facilitate reporting.
56 1. PKG_CONFIG_PATH can now be set in Local/Makefile;
57 wildcards will be expanded, values are collapsed.
59 2. The ${readsocket } expansion now takes an option to not shutdown the
60 connection after sending the query string. The default remains to do so.
62 3. An smtp transport option "hosts_noproxy_tls" to control whether multiple
63 deliveries on a single TCP connection can maintain a TLS connection
64 open. By default disabled for all hosts, doing so saves the cost of
65 making new TLS sessions, at the cost of having to proxy the data via
66 another process. Logging is also affected.
68 4. A malware connection type for the FPSCAND protocol.
70 5. An option for recipient verify callouts to hold the connection open for
71 further recipients and for delivery.
73 6. The reproducible build $SOURCE_DATE_EPOCH environment variable is now
76 7. Optionally, an alternate format for spool data-files which matches the
77 wire format - meaning more efficient reception and transmission (at the
78 cost of difficulty with standard Unix tools). Only used for messages
79 received using the ESMTP CHUNKING option, and when a new main-section
80 option "spool_wireformat" (false by default) is set.
82 8. New main configuration option "commandline_checks_require_admin" to
83 restrict who can use various introspection options.
85 9. New option modifier "no_check" for quota and quota_filecount
88 10. Variable $smtp_command_history returning a comma-sep list of recent
91 11. Millisecond timetamps in logs, on log_selector "millisec". Also affects
92 log elements QT, DT and D, and timstamps in debug output.
94 12. TCP Fast Open logging. As a server, logs when the SMTP banner was sent
95 while still in SYN_RECV state; as a client logs when the connection
96 is opened with a TFO cookie.
98 13. DKIM support for multiple signing, by domain and/or key-selector.
99 DKIM support for multiple hashes, and for alternate-identity tags.
100 Builtin macro with default list of signed headers.
101 Better syntax for specifying oversigning.
102 The DKIM ACL can override verification status, and status is visible in
105 14. Exipick understands -C|--config for an alternative Exim
108 15. TCP Fast Open used, with data-on-SYN, for client SMTP via SOCKS5 proxy,
109 for ${readsocket } expansions, and for ClamAV.
111 16. The "-be" expansion test mode now supports macros. Macros are expanded
112 in test lines, and new macros can be defined.
114 17. Support for server-side dual-certificate-stacks (eg. RSA + ECDSA).
120 1. Allow relative config file names for ".include"
122 2. A main-section config option "debug_store" to control the checks on
123 variable locations during store-reset. Normally false but can be enabled
124 when a memory corrution issue is suspected on a production system.
130 1. The new perl_taintmode option allows to run the embedded perl
131 interpreter in taint mode.
133 2. New log_selector: dnssec, adds a "DS" tag to acceptance and delivery lines.
135 3. Speculative debugging, via a "kill" option to the "control=debug" ACL
138 4. New expansion item ${sha3:<string>} / ${sha3_<N>:<string>}.
139 N can be 224, 256 (default), 384, 512.
140 With GnuTLS 3.5.0 or later, only.
142 5. Facility for named queues: A command-line argument can specify
143 the queue name for a queue operation, and an ACL modifier can set
144 the queue to be used for a message. A $queue_name variable gives
147 6. New expansion operators base32/base32d.
149 7. The CHUNKING ESMTP extension from RFC 3030. May give some slight
150 performance increase and network load decrease. Main config option
151 chunking_advertise_hosts, and smtp transport option hosts_try_chunking
154 8. LMDB lookup support, as Experimental. Patch supplied by Andrew Colin Kissa.
156 9. Expansion operator escape8bit, like escape but not touching newline etc..
158 10. Feature macros, generated from compile options. All start with "_HAVE_"
159 and go on with some roughly recognisable name. Driver macros, for
160 router, transport and authentication drivers; names starting with "_DRIVER_".
161 Option macros, for each configuration-file option; all start with "_OPT_".
162 Use the "-bP macros" command-line option to see what is present.
164 11. Integer values for options can take a "G" multiplier.
166 12. defer=pass option for the ACL control cutthrough_delivery, to reflect 4xx
167 returns from the target back to the initiator, rather than spooling the
170 13. New built-in constants available for tls_dhparam and default changed.
172 14. If built with EXPERIMENTAL_QUEUEFILE, a queuefile transport, for writing
173 out copies of the message spool files for use by 3rd-party scanners.
175 15. A new option on the smtp transport, hosts_try_fastopen. If the system
176 supports it (on Linux it must be enabled in the kernel by the sysadmin)
177 try to use RFC 7413 "TCP Fast Open". No data is sent on the SYN segment
178 but it permits a peer that also supports the facility to send its SMTP
179 banner immediately after the SYN,ACK segment rather then waiting for
180 another ACK - so saving up to one roundtrip time. Because it requires
181 previous communication with the peer (we save a cookie from it) this
182 will only become active on frequently-contacted destinations.
184 16. A new syslog_pid option to suppress PID duplication in syslog lines.
190 1. The ACL conditions regex and mime_regex now capture substrings
191 into numeric variables $regex1 to 9, like the "match" expansion condition.
193 2. New $callout_address variable records the address used for a spam=,
194 malware= or verify= callout.
196 3. Transports now take a "max_parallel" option, to limit concurrency.
198 4. Expansion operators ${ipv6norm:<string>} and ${ipv6denorm:<string>}.
199 The latter expands to a 8-element colon-sep set of hex digits including
200 leading zeroes. A trailing ipv4-style dotted-decimal set is converted
201 to hex. Pure ipv4 addresses are converted to IPv4-mapped IPv6.
202 The former operator strips leading zeroes and collapses the longest
203 set of 0-groups to a double-colon.
205 5. New "-bP config" support, to dump the effective configuration.
207 6. New $dkim_key_length variable.
209 7. New base64d and base64 expansion items (the existing str2b64 being a
210 synonym of the latter). Add support in base64 for certificates.
212 8. New main configuration option "bounce_return_linesize_limit" to
213 avoid oversize bodies in bounces. The default value matches RFC
216 9. New $initial_cwd expansion variable.
222 1. Support for using the system standard CA bundle.
224 2. New expansion items $config_file, $config_dir, containing the file
225 and directory name of the main configuration file. Also $exim_version.
227 3. New "malware=" support for Avast.
229 4. New "spam=" variant option for Rspamd.
231 5. Assorted options on malware= and spam= scanners.
233 6. A command-line option to write a comment into the logfile.
235 7. If built with EXPERIMENTAL_SOCKS feature enabled, the smtp transport can
236 be configured to make connections via socks5 proxies.
238 8. If built with EXPERIMENTAL_INTERNATIONAL, support is included for
239 the transmission of UTF-8 envelope addresses.
241 9. If built with EXPERIMENTAL_INTERNATIONAL, an expansion item for a commonly
242 used encoding of Maildir folder names.
244 10. A logging option for slow DNS lookups.
246 11. New ${env {<variable>}} expansion.
248 12. A non-SMTP authenticator using information from TLS client certificates.
250 13. Main option "tls_eccurve" for selecting an Elliptic Curve for TLS.
251 Patch originally by Wolfgang Breyha.
253 14. Main option "dns_trust_aa" for trusting your local nameserver at the
254 same level as DNSSEC.
260 1. If built with EXPERIMENTAL_DANE feature enabled, Exim will follow the
261 DANE SMTP draft to assess a secure chain of trust of the certificate
262 used to establish the TLS connection based on a TLSA record in the
263 domain of the sender.
265 2. The EXPERIMENTAL_TPDA feature has been renamed to EXPERIMENTAL_EVENT
266 and several new events have been created. The reason is because it has
267 been expanded beyond just firing events during the transport phase. Any
268 existing TPDA transport options will have to be rewritten to use a new
269 $event_name expansion variable in a condition. Refer to the
270 experimental-spec.txt for details and examples.
272 3. The EXPERIMENTAL_CERTNAMES features is an enhancement to verify that
273 server certs used for TLS match the result of the MX lookup. It does
274 not use the same mechanism as DANE.
284 1. If built with the EXPERIMENTAL_PROXY feature enabled, Exim can be
285 configured to expect an initial header from a proxy that will make the
286 actual external source IP:host be used in exim instead of the IP of the
287 proxy that is connecting to it.
289 2. New verify option header_names_ascii, which will check to make sure
290 there are no non-ASCII characters in header names. Exim itself handles
291 those non-ASCII characters, but downstream apps may not, so Exim can
292 detect and reject if those characters are present.
294 3. New expansion operator ${utf8clean:string} to replace malformed UTF8
295 codepoints with valid ones.
297 4. New malware type "sock". Talks over a Unix or TCP socket, sending one
298 command line and matching a regex against the return data for trigger
299 and a second regex to extract malware_name. The mail spoolfile name can
300 be included in the command line.
302 5. The smtp transport now supports options "tls_verify_hosts" and
303 "tls_try_verify_hosts". If either is set the certificate verification
304 is split from the encryption operation. The default remains that a failed
305 verification cancels the encryption.
307 6. New SERVERS override of default ldap server list. In the ACLs, an ldap
308 lookup can now set a list of servers to use that is different from the
311 7. New command-line option -C for exiqgrep to specify alternate exim.conf
312 file when searching the queue.
314 8. OCSP now supports GnuTLS also, if you have version 3.1.3 or later of that.
316 9. Support for DNSSEC on outbound connections.
318 10. New variables "tls_(in,out)_(our,peer)cert" and expansion item
319 "certextract" to extract fields from them. Hash operators md5 and sha1
320 work over them for generating fingerprints, and a new sha256 operator
323 11. PRDR is now supported dy default.
325 12. OCSP stapling is now supported by default.
327 13. If built with the EXPERIMENTAL_DSN feature enabled, Exim will output
328 Delivery Status Notification messages in MIME format, and negotiate
329 DSN features per RFC 3461.
335 1. New command-line option -bI:sieve will list all supported sieve extensions
336 of this Exim build on standard output, one per line.
337 ManageSieve (RFC 5804) providers managing scripts for use by Exim should
338 query this to establish the correct list to include in the protocol's
339 SIEVE capability line.
341 2. If the -n option is combined with the -bP option, then the name of an
342 emitted option is not output, only the value (if visible to you).
343 For instance, "exim -n -bP pid_file_path" should just emit a pathname
344 followed by a newline, and no other text.
346 3. When built with SUPPORT_TLS and USE_GNUTLS, the SMTP transport driver now
347 has a "tls_dh_min_bits" option, to set the minimum acceptable number of
348 bits in the Diffie-Hellman prime offered by a server (in DH ciphersuites)
349 acceptable for security. (Option accepted but ignored if using OpenSSL).
350 Defaults to 1024, the old value. May be lowered only to 512, or raised as
351 far as you like. Raising this may hinder TLS interoperability with other
352 sites and is not currently recommended. Lowering this will permit you to
353 establish a TLS session which is not as secure as you might like.
355 Unless you really know what you are doing, leave it alone.
357 4. If not built with DISABLE_DNSSEC, Exim now has the main option
358 dns_dnssec_ok; if set to 1 then Exim will initialise the resolver library
359 to send the DO flag to your recursive resolver. If you have a recursive
360 resolver, which can set the Authenticated Data (AD) flag in results, Exim
361 can now detect this. Exim does not perform validation itself, instead
362 relying upon a trusted path to the resolver.
364 Current status: work-in-progress; $sender_host_dnssec variable added.
366 5. DSCP support for outbound connections: on a transport using the smtp driver,
367 set "dscp = ef", for instance, to cause the connections to have the relevant
368 DSCP (IPv4 TOS or IPv6 TCLASS) value in the header.
370 Similarly for inbound connections, there is a new control modifier, dscp,
371 so "warn control = dscp/ef" in the connect ACL, or after authentication.
373 Supported values depend upon system libraries. "exim -bI:dscp" to list the
374 ones Exim knows of. You can also set a raw number 0..0x3F.
376 6. The -G command-line flag is no longer ignored; it is now equivalent to an
377 ACL setting "control = suppress_local_fixups". The -L command-line flag
378 is now accepted and forces use of syslog, with the provided tag as the
379 process name. A few other flags used by Sendmail are now accepted and
382 7. New cutthrough routing feature. Requested by a "control = cutthrough_delivery"
383 ACL modifier; works for single-recipient mails which are received on and
384 deliverable via SMTP. Using the connection made for a recipient verify,
385 if requested before the verify, or a new one made for the purpose while
386 the inbound connection is still active. The bulk of the mail item is copied
387 direct from the inbound socket to the outbound (as well as the spool file).
388 When the source notifies the end of data, the data acceptance by the destination
389 is negotiated before the acceptance is sent to the source. If the destination
390 does not accept the mail item, for example due to content-scanning, the item
391 is not accepted from the source and therefore there is no need to generate
392 a bounce mail. This is of benefit when providing a secondary-MX service.
393 The downside is that delays are under the control of the ultimate destination
396 The Received-by: header on items delivered by cutthrough is generated
397 early in reception rather than at the end; this will affect any timestamp
398 included. The log line showing delivery is recorded before that showing
399 reception; it uses a new ">>" tag instead of "=>".
401 To support the feature, verify-callout connections can now use ESMTP and TLS.
402 The usual smtp transport options are honoured, plus a (new, default everything)
403 hosts_verify_avoid_tls.
405 New variable families named tls_in_cipher, tls_out_cipher etc. are introduced
406 for specific access to the information for each connection. The old names
407 are present for now but deprecated.
409 Not yet supported: IGNOREQUOTA, SIZE, PIPELINING.
411 8. New expansion operators ${listnamed:name} to get the content of a named list
412 and ${listcount:string} to count the items in a list.
414 9. New global option "gnutls_allow_auto_pkcs11", defaults false. The GnuTLS
415 rewrite in 4.80 combines with GnuTLS 2.12.0 or later, to autoload PKCS11
416 modules. For some situations this is desirable, but we expect admin in
417 those situations to know they want the feature. More commonly, it means
418 that GUI user modules get loaded and are broken by the setuid Exim being
419 unable to access files specified in environment variables and passed
420 through, thus breakage. So we explicitly inhibit the PKCS11 initialisation
421 unless this new option is set.
423 Some older OS's with earlier versions of GnuTLS might not have pkcs11 ability,
424 so have also added a build option which can be used to build Exim with GnuTLS
425 but without trying to use any kind of PKCS11 support. Uncomment this in the
428 AVOID_GNUTLS_PKCS11=yes
430 10. The "acl = name" condition on an ACL now supports optional arguments.
431 New expansion item "${acl {name}{arg}...}" and expansion condition
432 "acl {{name}{arg}...}" are added. In all cases up to nine arguments
433 can be used, appearing in $acl_arg1 to $acl_arg9 for the called ACL.
434 Variable $acl_narg contains the number of arguments. If the ACL sets
435 a "message =" value this becomes the result of the expansion item,
436 or the value of $value for the expansion condition. If the ACL returns
437 accept the expansion condition is true; if reject, false. A defer
438 return results in a forced fail.
440 11. Routers and transports can now have multiple headers_add and headers_remove
441 option lines. The concatenated list is used.
443 12. New ACL modifier "remove_header" can remove headers before message gets
444 handled by routers/transports.
446 13. New dnsdb lookup pseudo-type "a+". A sequence of "a6" (if configured),
447 "aaaa" and "a" lookups is done and the full set of results returned.
449 14. New expansion variable $headers_added with content from ACL add_header
450 modifier (but not yet added to message).
452 15. New 8bitmime status logging option for received messages. Log field "M8S".
454 16. New authenticated_sender logging option, adding to log field "A".
456 17. New expansion variables $router_name and $transport_name. Useful
457 particularly for debug_print as -bt command-line option does not
458 require privilege whereas -d does.
460 18. If built with EXPERIMENTAL_PRDR, per-recipient data responses per a
461 proposed extension to SMTP from Eric Hall.
463 19. The pipe transport has gained the force_command option, to allow
464 decorating commands from user .forward pipe aliases with prefix
465 wrappers, for instance.
467 20. Callout connections can now AUTH; the same controls as normal delivery
470 21. Support for DMARC, using opendmarc libs, can be enabled. It adds new
471 options: dmarc_forensic_sender, dmarc_history_file, and dmarc_tld_file.
472 It adds new expansion variables $dmarc_ar_header, $dmarc_status,
473 $dmarc_status_text, and $dmarc_used_domain. It adds a new acl modifier
474 dmarc_status. It adds new control flags dmarc_disable_verify and
475 dmarc_enable_forensic. The default for the dmarc_tld_file option is
476 "/etc/exim/opendmarc.tlds" and can be changed via EDITME.
478 22. Add expansion variable $authenticated_fail_id, which is the username
479 provided to the authentication method which failed. It is available
480 for use in subsequent ACL processing (typically quit or notquit ACLs).
482 23. New ACL modifier "udpsend" can construct a UDP packet to send to a given
485 24. New ${hexquote:..string..} expansion operator converts non-printable
486 characters in the string to \xNN form.
488 25. Experimental TPDA (Transport Post Delivery Action) function added.
489 Patch provided by Axel Rau.
491 26. Experimental Redis lookup added. Patch provided by Warren Baker.
497 1. New authenticator driver, "gsasl". Server-only (at present).
498 This is a SASL interface, licensed under GPL, which can be found at
499 http://www.gnu.org/software/gsasl/.
500 This system does not provide sources of data for authentication, so
501 careful use needs to be made of the conditions in Exim.
503 2. New authenticator driver, "heimdal_gssapi". Server-only.
504 A replacement for using cyrus_sasl with Heimdal, now that $KRB5_KTNAME
505 is no longer honoured for setuid programs by Heimdal. Use the
506 "server_keytab" option to point to the keytab.
508 3. The "pkg-config" system can now be used when building Exim to reference
509 cflags and library information for lookups and authenticators, rather
510 than having to update "CFLAGS", "AUTH_LIBS", "LOOKUP_INCLUDE" and
511 "LOOKUP_LIBS" directly. Similarly for handling the TLS library support
512 without adjusting "TLS_INCLUDE" and "TLS_LIBS".
514 In addition, setting PCRE_CONFIG=yes will query the pcre-config tool to
515 find the headers and libraries for PCRE.
517 4. New expansion variable $tls_bits.
519 5. New lookup type, "dbmjz". Key is an Exim list, the elements of which will
520 be joined together with ASCII NUL characters to construct the key to pass
521 into the DBM library. Can be used with gsasl to access sasldb2 files as
524 6. OpenSSL now supports TLS1.1 and TLS1.2 with OpenSSL 1.0.1.
526 Avoid release 1.0.1a if you can. Note that the default value of
527 "openssl_options" is no longer "+dont_insert_empty_fragments", as that
528 increased susceptibility to attack. This may still have interoperability
529 implications for very old clients (see version 4.31 change 37) but
530 administrators can choose to make the trade-off themselves and restore
531 compatibility at the cost of session security.
533 7. Use of the new expansion variable $tls_sni in the main configuration option
534 tls_certificate will cause Exim to re-expand the option, if the client
535 sends the TLS Server Name Indication extension, to permit choosing a
536 different certificate; tls_privatekey will also be re-expanded. You must
537 still set these options to expand to valid files when $tls_sni is not set.
539 The SMTP Transport has gained the option tls_sni, which will set a hostname
540 for outbound TLS sessions, and set $tls_sni too.
542 A new log_selector, +tls_sni, has been added, to log received SNI values
543 for Exim as a server.
545 8. The existing "accept_8bitmime" option now defaults to true. This means
546 that Exim is deliberately not strictly RFC compliant. We're following
547 Dan Bernstein's advice in http://cr.yp.to/smtp/8bitmime.html by default.
548 Those who disagree, or know that they are talking to mail servers that,
549 even today, are not 8-bit clean, need to turn off this option.
551 9. Exim can now be started with -bw (with an optional timeout, given as
552 -bw<timespec>). With this, stdin at startup is a socket that is
553 already listening for connections. This has a more modern name of
554 "socket activation", but forcing the activated socket to fd 0. We're
555 interested in adding more support for modern variants.
557 10. ${eval } now uses 64-bit values on supporting platforms. A new "G" suffix
558 for numbers indicates multiplication by 1024^3.
560 11. The GnuTLS support has been revamped; the three options gnutls_require_kx,
561 gnutls_require_mac & gnutls_require_protocols are no longer supported.
562 tls_require_ciphers is now parsed by gnutls_priority_init(3) as a priority
563 string, documentation for which is at:
564 http://www.gnutls.org/manual/html_node/Priority-Strings.html
566 SNI support has been added to Exim's GnuTLS integration too.
568 For sufficiently recent GnuTLS libraries, ${randint:..} will now use
569 gnutls_rnd(), asking for GNUTLS_RND_NONCE level randomness.
571 12. With OpenSSL, if built with EXPERIMENTAL_OCSP, a new option tls_ocsp_file
572 is now available. If the contents of the file are valid, then Exim will
573 send that back in response to a TLS status request; this is OCSP Stapling.
574 Exim will not maintain the contents of the file in any way: administrators
575 are responsible for ensuring that it is up-to-date.
577 See "experimental-spec.txt" for more details.
579 13. ${lookup dnsdb{ }} supports now SPF record types. They are handled
580 identically to TXT record lookups.
582 14. New expansion variable $tod_epoch_l for higher-precision time.
584 15. New global option tls_dh_max_bits, defaulting to current value of NSS
585 hard-coded limit of DH ephemeral bits, to fix interop problems caused by
586 GnuTLS 2.12 library recommending a bit count higher than NSS supports.
588 16. tls_dhparam now used by both OpenSSL and GnuTLS, can be path or identifier.
589 Option can now be a path or an identifier for a standard prime.
590 If unset, we use the DH prime from section 2.2 of RFC 5114, "ike23".
591 Set to "historic" to get the old GnuTLS behaviour of auto-generated DH
594 17. SSLv2 now disabled by default in OpenSSL. (Never supported by GnuTLS).
595 Use "openssl_options -no_sslv2" to re-enable support, if your OpenSSL
596 install was not built with OPENSSL_NO_SSL2 ("no-ssl2").
602 1. New options for the ratelimit ACL condition: /count= and /unique=.
603 The /noupdate option has been replaced by a /readonly option.
605 2. The SMTP transport's protocol option may now be set to "smtps", to
606 use SSL-on-connect outbound.
608 3. New variable $av_failed, set true if the AV scanner deferred; ie, when
609 there is a problem talking to the AV scanner, or the AV scanner running.
611 4. New expansion conditions, "inlist" and "inlisti", which take simple lists
612 and check if the search item is a member of the list. This does not
613 support named lists, but does subject the list part to string expansion.
615 5. Unless the new EXPAND_LISTMATCH_RHS build option is set when Exim was
616 built, Exim no longer performs string expansion on the second string of
617 the match_* expansion conditions: "match_address", "match_domain",
618 "match_ip" & "match_local_part". Named lists can still be used.
624 1. The global option "dns_use_edns0" may be set to coerce EDNS0 usage on
625 or off in the resolver library.
631 1. In addition to the existing LDAP and LDAP/SSL ("ldaps") support, there
632 is now LDAP/TLS support, given sufficiently modern OpenLDAP client
633 libraries. The following global options have been added in support of
634 this: ldap_ca_cert_dir, ldap_ca_cert_file, ldap_cert_file, ldap_cert_key,
635 ldap_cipher_suite, ldap_require_cert, ldap_start_tls.
637 2. The pipe transport now takes a boolean option, "freeze_signal", default
638 false. When true, if the external delivery command exits on a signal then
639 Exim will freeze the message in the queue, instead of generating a bounce.
641 3. Log filenames may now use %M as an escape, instead of %D (still available).
642 The %M pattern expands to yyyymm, providing month-level resolution.
644 4. The $message_linecount variable is now updated for the maildir_tag option,
645 in the same way as $message_size, to reflect the real number of lines,
646 including any header additions or removals from transport.
648 5. When contacting a pool of SpamAssassin servers configured in spamd_address,
649 Exim now selects entries randomly, to better scale in a cluster setup.
655 1. SECURITY FIX: privilege escalation flaw fixed. On Linux (and only Linux)
656 the flaw permitted the Exim run-time user to cause root to append to
657 arbitrary files of the attacker's choosing, with the content based
658 on content supplied by the attacker.
660 2. Exim now supports loading some lookup types at run-time, using your
661 platform's dlopen() functionality. This has limited platform support
662 and the intention is not to support every variant, it's limited to
663 dlopen(). This permits the main Exim binary to not be linked against
664 all the libraries needed for all the lookup types.
670 NOTE: this version is not guaranteed backwards-compatible, please read the
671 items below carefully
673 1. A new main configuration option, "openssl_options", is available if Exim
674 is built with SSL support provided by OpenSSL. The option allows
675 administrators to specify OpenSSL options to be used on connections;
676 typically this is to set bug compatibility features which the OpenSSL
677 developers have not enabled by default. There may be security
678 consequences for certain options, so these should not be changed
681 2. A new pipe transport option, "permit_coredumps", may help with problem
682 diagnosis in some scenarios. Note that Exim is typically installed as
683 a setuid binary, which on most OSes will inhibit coredumps by default,
684 so that safety mechanism would have to be overridden for this option to
685 be able to take effect.
687 3. ClamAV 0.95 is now required for ClamAV support in Exim, unless
688 Local/Makefile sets: WITH_OLD_CLAMAV_STREAM=yes
689 Note that this switches Exim to use a new API ("INSTREAM") and a future
690 release of ClamAV will remove support for the old API ("STREAM").
692 The av_scanner option, when set to "clamd", now takes an optional third
693 part, "local", which causes Exim to pass a filename to ClamAV instead of
694 the file content. This is the same behaviour as when clamd is pointed at
695 a Unix-domain socket. For example:
697 av_scanner = clamd:192.0.2.3 1234:local
699 ClamAV's ExtendedDetectionInfo response format is now handled.
701 4. There is now a -bmalware option, restricted to admin users. This option
702 takes one parameter, a filename, and scans that file with Exim's
703 malware-scanning framework. This is intended purely as a debugging aid
704 to ensure that Exim's scanning is working, not to replace other tools.
705 Note that the ACL framework is not invoked, so if av_scanner references
706 ACL variables without a fallback then this will fail.
708 5. There is a new expansion operator, "reverse_ip", which will reverse IP
709 addresses; IPv4 into dotted quad, IPv6 into dotted nibble. Examples:
711 ${reverse_ip:192.0.2.4}
713 ${reverse_ip:2001:0db8:c42:9:1:abcd:192.0.2.3}
714 -> 3.0.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2
716 6. There is a new ACL control called "debug", to enable debug logging.
717 This allows selective logging of certain incoming transactions within
718 production environments, with some care. It takes two options, "tag"
719 and "opts"; "tag" is included in the filename of the log and "opts"
720 is used as per the -d<options> command-line option. Examples, which
721 don't all make sense in all contexts:
724 control = debug/tag=.$sender_host_address
725 control = debug/opts=+expand+acl
726 control = debug/tag=.$message_exim_id/opts=+expand
728 7. It has always been implicit in the design and the documentation that
729 "the Exim user" is not root. src/EDITME said that using root was
730 "very strongly discouraged". This is not enough to keep people from
731 shooting themselves in the foot in days when many don't configure Exim
732 themselves but via package build managers. The security consequences of
733 running various bits of network code are severe if there should be bugs in
734 them. As such, the Exim user may no longer be root. If configured
735 statically, Exim will refuse to build. If configured as ref:user then Exim
736 will exit shortly after start-up. If you must shoot yourself in the foot,
737 then henceforth you will have to maintain your own local patches to strip
740 8. There is a new expansion condition, bool_lax{}. Where bool{} uses the ACL
741 condition logic to determine truth/failure and will fail to expand many
742 strings, bool_lax{} uses the router condition logic, where most strings
744 Note: bool{00} is false, bool_lax{00} is true.
746 9. Routers now support multiple "condition" tests.
748 10. There is now a runtime configuration option "tcp_wrappers_daemon_name".
749 Setting this allows an admin to define which entry in the tcpwrappers
750 config file will be used to control access to the daemon. This option
751 is only available when Exim is built with USE_TCP_WRAPPERS. The
752 default value is set at build time using the TCP_WRAPPERS_DAEMON_NAME
755 11. [POSSIBLE CONFIG BREAKAGE] The default value for system_filter_user is now
756 the Exim run-time user, instead of root.
758 12. [POSSIBLE CONFIG BREAKAGE] ALT_CONFIG_ROOT_ONLY is no longer optional and
759 is forced on. This is mitigated by the new build option
760 TRUSTED_CONFIG_LIST which defines a list of configuration files which
761 are trusted; one per line. If a config file is owned by root and matches
762 a pathname in the list, then it may be invoked by the Exim build-time
763 user without Exim relinquishing root privileges.
765 13. [POSSIBLE CONFIG BREAKAGE] The Exim user is no longer automatically
766 trusted to supply -D<Macro[=Value]> overrides on the command-line. Going
767 forward, we recommend using TRUSTED_CONFIG_LIST with shim configs that
768 include the main config. As a transition mechanism, we are temporarily
769 providing a work-around: the new build option WHITELIST_D_MACROS provides
770 a colon-separated list of macro names which may be overridden by the Exim
771 run-time user. The values of these macros are constrained to the regex
772 ^[A-Za-z0-9_/.-]*$ (which explicitly does allow for empty values).
778 1. TWO SECURITY FIXES: one relating to mail-spools which are globally
779 writable, the other to locking of MBX folders (not mbox).
781 2. MySQL stored procedures are now supported.
783 3. The dkim_domain transport option is now a list, not a single string, and
784 messages will be signed for each element in the list (discarding
787 4. The 4.70 release unexpectedly changed the behaviour of dnsdb TXT lookups
788 in the presence of multiple character strings within the RR. Prior to 4.70,
789 only the first string would be returned. The dnsdb lookup now, by default,
790 preserves the pre-4.70 semantics, but also now takes an extended output
791 separator specification. The separator can be followed by a semicolon, to
792 concatenate the individual text strings together with no join character,
793 or by a comma and a second separator character, in which case the text
794 strings within a TXT record are joined on that second character.
795 Administrators are reminded that DNS provides no ordering guarantees
796 between multiple records in an RRset. For example:
798 foo.example. IN TXT "a" "b" "c"
799 foo.example. IN TXT "d" "e" "f"
801 ${lookup dnsdb{>/ txt=foo.example}} -> "a/d"
802 ${lookup dnsdb{>/; txt=foo.example}} -> "def/abc"
803 ${lookup dnsdb{>/,+ txt=foo.example}} -> "a+b+c/d+e+f"
809 1. Native DKIM support without an external library.
810 (Note that if no action to prevent it is taken, a straight upgrade will
811 result in DKIM verification of all signed incoming emails. See spec
812 for details on conditionally disabling)
814 2. Experimental DCC support via dccifd (contributed by Wolfgang Breyha).
816 3. There is now a bool{} expansion condition which maps certain strings to
817 true/false condition values (most likely of use in conjunction with the
818 and{} expansion operator).
820 4. The $spam_score, $spam_bar and $spam_report variables are now available
823 5. exim -bP now supports "macros", "macro_list" or "macro MACRO_NAME" as
824 options, provided that Exim is invoked by an admin_user.
826 6. There is a new option gnutls_compat_mode, when linked against GnuTLS,
827 which increases compatibility with older clients at the cost of decreased
828 security. Don't set this unless you need to support such clients.
830 7. There is a new expansion operator, ${randint:...} which will produce a
831 "random" number less than the supplied integer. This randomness is
832 not guaranteed to be cryptographically strong, but depending upon how
833 Exim was built may be better than the most naive schemes.
835 8. Exim now explicitly ensures that SHA256 is available when linked against
838 9. The transport_filter_timeout option now applies to SMTP transports too.
844 1. Preliminary DKIM support in Experimental.
850 1. The body_linecount and body_zerocount C variables are now exported in the
853 2. When a dnslists lookup succeeds, the key that was looked up is now placed
854 in $dnslist_matched. When the key is an IP address, it is not reversed in
855 this variable (though it is, of course, in the actual lookup). In simple
858 deny dnslists = spamhaus.example
860 the key is also available in another variable (in this case,
861 $sender_host_address). In more complicated cases, however, this is not
862 true. For example, using a data lookup might generate a dnslists lookup
865 deny dnslists = spamhaus.example/<|192.168.1.2|192.168.6.7|...
867 If this condition succeeds, the value in $dnslist_matched might be
868 192.168.6.7 (for example).
870 3. Authenticators now have a client_condition option. When Exim is running as
871 a client, it skips an authenticator whose client_condition expansion yields
872 "0", "no", or "false". This can be used, for example, to skip plain text
873 authenticators when the connection is not encrypted by a setting such as:
875 client_condition = ${if !eq{$tls_cipher}{}}
877 Note that the 4.67 documentation states that $tls_cipher contains the
878 cipher used for incoming messages. In fact, during SMTP delivery, it
879 contains the cipher used for the delivery. The same is true for
882 4. There is now a -Mvc <message-id> option, which outputs a copy of the
883 message to the standard output, in RFC 2822 format. The option can be used
884 only by an admin user.
886 5. There is now a /noupdate option for the ratelimit ACL condition. It
887 computes the rate and checks the limit as normal, but it does not update
888 the saved data. This means that, in relevant ACLs, it is possible to lookup
889 the existence of a specified (or auto-generated) ratelimit key without
890 incrementing the ratelimit counter for that key.
892 In order for this to be useful, another ACL entry must set the rate
893 for the same key somewhere (otherwise it will always be zero).
898 # Read the rate; if it doesn't exist or is below the maximum
900 deny ratelimit = 100 / 5m / strict / noupdate
901 log_message = RATE: $sender_rate / $sender_rate_period \
902 (max $sender_rate_limit)
904 [... some other logic and tests...]
906 warn ratelimit = 100 / 5m / strict / per_cmd
907 log_message = RATE UPDATE: $sender_rate / $sender_rate_period \
908 (max $sender_rate_limit)
909 condition = ${if le{$sender_rate}{$sender_rate_limit}}
913 6. The variable $max_received_linelength contains the number of bytes in the
914 longest line that was received as part of the message, not counting the
915 line termination character(s).
917 7. Host lists can now include +ignore_defer and +include_defer, analagous to
918 +ignore_unknown and +include_unknown. These options should be used with
919 care, probably only in non-critical host lists such as whitelists.
921 8. There's a new option called queue_only_load_latch, which defaults true.
922 If set false when queue_only_load is greater than zero, Exim re-evaluates
923 the load for each incoming message in an SMTP session. Otherwise, once one
924 message is queued, the remainder are also.
926 9. There is a new ACL, specified by acl_smtp_notquit, which is run in most
927 cases when an SMTP session ends without sending QUIT. However, when Exim
928 itself is is bad trouble, such as being unable to write to its log files,
929 this ACL is not run, because it might try to do things (such as write to
930 log files) that make the situation even worse.
932 Like the QUIT ACL, this new ACL is provided to make it possible to gather
933 statistics. Whatever it returns (accept or deny) is immaterial. The "delay"
934 modifier is forbidden in this ACL.
936 When the NOTQUIT ACL is running, the variable $smtp_notquit_reason is set
937 to a string that indicates the reason for the termination of the SMTP
938 connection. The possible values are:
940 acl-drop Another ACL issued a "drop" command
941 bad-commands Too many unknown or non-mail commands
942 command-timeout Timeout while reading SMTP commands
943 connection-lost The SMTP connection has been lost
944 data-timeout Timeout while reading message data
945 local-scan-error The local_scan() function crashed
946 local-scan-timeout The local_scan() function timed out
947 signal-exit SIGTERM or SIGINT
948 synchronization-error SMTP synchronization error
949 tls-failed TLS failed to start
951 In most cases when an SMTP connection is closed without having received
952 QUIT, Exim sends an SMTP response message before actually closing the
953 connection. With the exception of acl-drop, the default message can be
954 overridden by the "message" modifier in the NOTQUIT ACL. In the case of a
955 "drop" verb in another ACL, it is the message from the other ACL that is
958 10. For MySQL and PostgreSQL lookups, it is now possible to specify a list of
959 servers with individual queries. This is done by starting the query with
960 "servers=x:y:z;", where each item in the list may take one of two forms:
962 (1) If it is just a host name, the appropriate global option (mysql_servers
963 or pgsql_servers) is searched for a host of the same name, and the
964 remaining parameters (database, user, password) are taken from there.
966 (2) If it contains any slashes, it is taken as a complete parameter set.
968 The list of servers is used in exactly the same was as the global list.
969 Once a connection to a server has happened and a query has been
970 successfully executed, processing of the lookup ceases.
972 This feature is intended for use in master/slave situations where updates
973 are occurring, and one wants to update a master rather than a slave. If the
974 masters are in the list for reading, you might have:
976 mysql_servers = slave1/db/name/pw:slave2/db/name/pw:master/db/name/pw
978 In an updating lookup, you could then write
980 ${lookup mysql{servers=master; UPDATE ...}
982 If, on the other hand, the master is not to be used for reading lookups:
984 pgsql_servers = slave1/db/name/pw:slave2/db/name/pw
986 you can still update the master by
988 ${lookup pgsql{servers=master/db/name/pw; UPDATE ...}
990 11. The message_body_newlines option (default FALSE, for backwards
991 compatibility) can be used to control whether newlines are present in
992 $message_body and $message_body_end. If it is FALSE, they are replaced by
999 1. There is a new log selector called smtp_no_mail, which is not included in
1000 the default setting. When it is set, a line is written to the main log
1001 whenever an accepted SMTP connection terminates without having issued a
1004 2. When an item in a dnslists list is followed by = and & and a list of IP
1005 addresses, the behaviour was not clear when the lookup returned more than
1006 one IP address. This has been solved by the addition of == and =& for "all"
1007 rather than the default "any" matching.
1009 3. Up till now, the only control over which cipher suites GnuTLS uses has been
1010 for the cipher algorithms. New options have been added to allow some of the
1011 other parameters to be varied.
1013 4. There is a new compile-time option called ENABLE_DISABLE_FSYNC. When it is
1014 set, Exim compiles a runtime option called disable_fsync.
1016 5. There is a new variable called $smtp_count_at_connection_start.
1018 6. There's a new control called no_pipelining.
1020 7. There are two new variables called $sending_ip_address and $sending_port.
1021 These are set whenever an SMTP connection to another host has been set up.
1023 8. The expansion of the helo_data option in the smtp transport now happens
1024 after the connection to the server has been made.
1026 9. There is a new expansion operator ${rfc2047d: that decodes strings that
1027 are encoded as per RFC 2047.
1029 10. There is a new log selector called "pid", which causes the current process
1030 id to be added to every log line, in square brackets, immediately after the
1033 11. Exim has been modified so that it flushes SMTP output before implementing
1034 a delay in an ACL. It also flushes the output before performing a callout,
1035 as this can take a substantial time. These behaviours can be disabled by
1036 obeying control = no_delay_flush or control = no_callout_flush,
1037 respectively, at some earlier stage of the connection.
1039 12. There are two new expansion conditions that iterate over a list. They are
1040 called forany and forall.
1042 13. There's a new global option called dsn_from that can be used to vary the
1043 contents of From: lines in bounces and other automatically generated
1044 messages ("delivery status notifications" - hence the name of the option).
1046 14. The smtp transport has a new option called hosts_avoid_pipelining.
1048 15. By default, exigrep does case-insensitive matches. There is now a -I option
1049 that makes it case-sensitive.
1051 16. A number of new features ("addresses", "map", "filter", and "reduce") have
1052 been added to string expansions to make it easier to process lists of
1053 items, typically addresses.
1055 17. There's a new ACL modifier called "continue". It does nothing of itself,
1056 and processing of the ACL always continues with the next condition or
1057 modifier. It is provided so that the side effects of expanding its argument
1060 18. It is now possible to use newline and other control characters (those with
1061 values less than 32, plus DEL) as separators in lists.
1063 19. The exigrep utility now has a -v option, which inverts the matching
1066 20. The host_find_failed option in the manualroute router can now be set to
1073 No new features were added to 4.66.
1079 No new features were added to 4.65.
1085 1. ACL variables can now be given arbitrary names, as long as they start with
1086 "acl_c" or "acl_m" (for connection variables and message variables), are at
1087 least six characters long, with the sixth character being either a digit or
1090 2. There is a new ACL modifier called log_reject_target. It makes it possible
1091 to specify which logs are used for messages about ACL rejections.
1093 3. There is a new authenticator called "dovecot". This is an interface to the
1094 authentication facility of the Dovecot POP/IMAP server, which can support a
1095 number of authentication methods.
1097 4. The variable $message_headers_raw provides a concatenation of all the
1098 messages's headers without any decoding. This is in contrast to
1099 $message_headers, which does RFC2047 decoding on the header contents.
1101 5. In a DNS black list, if two domain names, comma-separated, are given, the
1102 second is used first to do an initial check, making use of any IP value
1103 restrictions that are set. If there is a match, the first domain is used,
1104 without any IP value restrictions, to get the TXT record.
1106 6. All authenticators now have a server_condition option.
1108 7. There is a new command-line option called -Mset. It is useful only in
1109 conjunction with -be (that is, when testing string expansions). It must be
1110 followed by a message id; Exim loads the given message from its spool
1111 before doing the expansions.
1113 8. Another similar new command-line option is called -bem. It operates like
1114 -be except that it must be followed by the name of a file that contains a
1117 9. When an address is delayed because of a 4xx response to a RCPT command, it
1118 is now the combination of sender and recipient that is delayed in
1119 subsequent queue runs until its retry time is reached.
1121 10. Unary negation and the bitwise logical operators and, or, xor, not, and
1122 shift, have been added to the eval: and eval10: expansion items.
1124 11. The variables $interface_address and $interface_port have been renamed
1125 as $received_ip_address and $received_port, to make it clear that they
1126 relate to message reception rather than delivery. (The old names remain
1127 available for compatibility.)
1129 12. The "message" modifier can now be used on "accept" and "discard" acl verbs
1130 to vary the message that is sent when an SMTP command is accepted.
1136 1. There is a new Boolean option called filter_prepend_home for the redirect
1139 2. There is a new acl, set by acl_not_smtp_start, which is run right at the
1140 start of receiving a non-SMTP message, before any of the message has been
1143 3. When an SMTP error message is specified in a "message" modifier in an ACL,
1144 or in a :fail: or :defer: message in a redirect router, Exim now checks the
1145 start of the message for an SMTP error code.
1147 4. There is a new parameter for LDAP lookups called "referrals", which takes
1148 one of the settings "follow" (the default) or "nofollow".
1150 5. Version 20070721.2 of exipick now included, offering these new options:
1152 After all other sorting options have bee processed, reverse order
1153 before displaying messages (-R is synonym).
1155 Randomize order of matching messages before displaying.
1157 Instead of displaying the matching messages, display the sum
1159 --sort <variable>[,<variable>...]
1160 Before displaying matching messages, sort the messages according to
1161 each messages value for each variable.
1163 Negate the value for every test (returns inverse output from the
1164 same criteria without --not).
1170 1. The ${readsocket expansion item now supports Internet domain sockets as well
1171 as Unix domain sockets. If the first argument begins "inet:", it must be of
1172 the form "inet:host:port". The port is mandatory; it may be a number or the
1173 name of a TCP port in /etc/services. The host may be a name, or it may be an
1174 IP address. An ip address may optionally be enclosed in square brackets.
1175 This is best for IPv6 addresses. For example:
1177 ${readsocket{inet:[::1]:1234}{<request data>}...
1179 Only a single host name may be given, but if looking it up yield more than
1180 one IP address, they are each tried in turn until a connection is made. Once
1181 a connection has been made, the behaviour is as for ${readsocket with a Unix
1184 2. If a redirect router sets up file or pipe deliveries for more than one
1185 incoming address, and the relevant transport has batch_max set greater than
1186 one, a batch delivery now occurs.
1188 3. The appendfile transport has a new option called maildirfolder_create_regex.
1189 Its value is a regular expression. For a maildir delivery, this is matched
1190 against the maildir directory; if it matches, Exim ensures that a
1191 maildirfolder file is created alongside the new, cur, and tmp directories.
1197 The documentation is up-to-date for the 4.61 release. Major new features since
1198 the 4.60 release are:
1200 . An option called disable_ipv6, to disable the use of IPv6 completely.
1202 . An increase in the number of ACL variables to 20 of each type.
1204 . A change to use $auth1, $auth2, and $auth3 in authenticators instead of $1,
1205 $2, $3, (though those are still set) because the numeric variables get used
1206 for other things in complicated expansions.
1208 . The default for rfc1413_query_timeout has been changed from 30s to 5s.
1210 . It is possible to use setclassresources() on some BSD OS to control the
1211 resources used in pipe deliveries.
1213 . A new ACL modifier called add_header, which can be used with any verb.
1215 . More errors are detectable in retry rules.
1217 There are a number of other additions too.
1223 The documentation is up-to-date for the 4.60 release. Major new features since
1224 the 4.50 release are:
1226 . Support for SQLite.
1228 . Support for IGNOREQUOTA in LMTP.
1230 . Extensions to the "submission mode" features.
1232 . Support for Client SMTP Authorization (CSA).
1234 . Support for ratelimiting hosts and users.
1236 . New expansion items to help with the BATV "prvs" scheme.
1238 . A "match_ip" condition, that matches an IP address against a list.
1240 There are many more minor changes.
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