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Diffstat (limited to 'RELEASE_NOTES-3.6')
| -rw-r--r-- | RELEASE_NOTES-3.6 | 277 |
1 files changed, 277 insertions, 0 deletions
diff --git a/RELEASE_NOTES-3.6 b/RELEASE_NOTES-3.6 new file mode 100644 index 0000000..d8ac90c --- /dev/null +++ b/RELEASE_NOTES-3.6 @@ -0,0 +1,277 @@ +This is the Postfix 3.6 (stable) release. + +The stable Postfix release is called postfix-3.6.x where 3=major +release number, 6=minor release number, x=patchlevel. The stable +release never changes except for patches that address bugs or +emergencies. Patches change the patchlevel and the release date. + +New features are developed in snapshot releases. These are called +postfix-3.7-yyyymmdd where yyyymmdd is the release date (yyyy=year, +mm=month, dd=day). Patches are never issued for snapshot releases; +instead, a new snapshot is released. + +The mail_release_date configuration parameter (format: yyyymmdd) +specifies the release date of a stable release or snapshot release. + +If you upgrade from Postfix 3.4 or earlier, read RELEASE_NOTES-3.5 +before proceeding. + +License change +--------------- + +This software is distributed with a dual license: in addition to the +historical IBM Public License 1.0, it is now also distributed with the +more recent Eclipse Public License 2.0. Recipients can choose to take +the software under the license of their choice. Those who are more +comfortable with the IPL can continue with that license. + +Major changes - internal protocol identification +------------------------------------------------ + +[Incompat 20200920] Internal protocols have changed. You need to +"postfix stop" before updating, or before backing out to an earlier +release, otherwise long-running daemons (pickup, qmgr, verify, tlsproxy, +postscreen) may fail to communicate with the rest of Postfix, causing +mail delivery delays until Postfix is restarted. + +This change does not affect message files in Postfix queue directories, +only the communication between running Postfix programs. + +With this change, every Postfix internal service, including the postdrop +command, announces the name of its protocol before doing any other I/O. +Every Postfix client program, including the Postfix sendmail command, +will verify that the protocol name matches what it is supposed to be. + +The purpose of this change is to produce better error messages, for +example, when someone configures the discard daemon as a bounce +service in master.cf, or vice versa. + +This change may break third-party programs that implement a +Postfix-internal protocol such as qpsmtpd. Such programs have never +been supported. Fortunately, this will be an easy fix: look at the +first data from the cleanup daemon: if it is a protocol announcement, +you're talking to Postfix 3.6 or later. That's the only real change. + +Major changes - tls +------------------- + +[Incompat 20200705] The minimum supported OpenSSL version is 1.1.1, +which will reach the end of life by 2023-09-11. Postfix 3.6 is +expected to reach the end of support in 2025. Until then, Postfix +will be updated as needed for compatibility with OpenSSL. + +The default fingerprint digest has changed from md5 to sha256 (Postfix +3.6 with compatibility_level >= 3.6). With a lower compatibility_level +setting, Postfix defaults to using md5, and logs a warning when a Postfix +configuration specifies no explicit digest type. + +Export-grade Diffie-Hellman key exchange is no longer supported, +and the tlsproxy_tls_dh512_param_file parameter is ignored, + +[Feature 20200906] The tlstype.pl helper script by Viktor Dukhovni +reports TLS information per message delivery. This processes output +from the collate.pl script. See auxiliary/collate/README.tlstype and +auxiliary/collate/tlstype.pl. + +Major changes - compatibility level +----------------------------------- + +[Feature 20210109] Starting with Postfix version 3.6, the compatibility +level is "3.6". In future Postfix releases, the compatibility level will +be the Postfix version that introduced the last incompatible change. The +level is formatted as 'major.minor.patch', where 'patch' is usually +omitted and defaults to zero. Earlier compatibility levels are 0, 1 and 2. + +This also introduces main.cf and master.cf support for the <=level, +<level, and other operators to compare compatibility levels. With the +standard <=, <, etc. operators, compatibility level 3.10 would be less +than 3.9, which is undesirable. + +Major changes - services(5) override +------------------------------------ + +[Feature 20210418] Postfix no longer uses the services(5) database +to look up the TCP ports for SMTP and LMTP services. Instead, this +information is configured with the new known_tcp_ports configuration +parameter (default: lmtp=24, smtp=25, smtps=submissions=465, +submission=587). When a service is not specified in known_tcp_ports, +Postfix will still query the services(5) database. + +Major changes - local_login_sender_maps +--------------------------------------- + +[Feature 20201025] Fine-grained control over the envelope sender address +for submission with the Postfix sendmail (or postdrop) commands. + +The local_login_sender_maps parameter (default: static:*) specifies +a list of lookup tables that are searched by the UNIX login name, and +that return a list of allowed envelope sender patterns separated by +space or comma. The default is backwards-compatible: every user may +specify any sender envelope address. + +This feature is enforced by the postdrop command. When no UNIX login +name is available, the postdrop command will prepend "uid:" to the +numerical UID and use that instead. + +This feature ignores address extensions in the user-specified +envelope sender address. + +Besides the special pattern "*" which allows any sender address, +there are "<>" which matches an empty sender address, and the +"@domain" wildcard pattern. More information about those can be found +in the postconf(5) manpage. + +Example: + +/etc/postfix/main.cf: + # Allow root and postfix full control, anyone else can only + # send mail as themselves. Use "uid:" followed by the numerical + # UID when the UID has no entry in the UNIX password file. + local_login_sender_maps = + inline:{ { root = *}, { postfix = * } }, + pcre:/etc/postfix/login_senders + +/etc/postfix/login_senders: + # Allow both the bare username and the user@domain forms. + /(.+)/ $1 $1@example.com + +Major changes - order of relay and recipient restrictions +--------------------------------------------------------- + +[Incompat 20210131] With smtpd_relay_before_recipient_restrictions=yes, +the Postfix SMTP server will evaluate smtpd_relay_restrictions before +smtpd_recipient_restrictions. This is the default behavior with +compatibility_level >= 3.6. + +This change makes the implemented behavior consistent with existing +documentation. There is a backwards-compatibility warning that allows +users to freeze historical behavior. See COMPATIBILITY_README for +details. + +Major changes - respectful logging +---------------------------------- + +[Feature 20210220] Postfix version 3.6 deprecates terminology +that implies white is better than black. Instead, Postfix prefers +'allowlist', 'denylist', and variations on those words. This change +affects Postfix documentation, and postscreen parameters and logging. + +To keep the old postscreen logging set "respectful_logging = no" +in main.cf. + +Noel Jones assisted with the initial transition. + +Changes in documentation +------------------------ + +Postfix documentation was updated to use 'allowlist', 'denylist', etc. +These documentation changes do not affect Postfix behavior. + +Changes in parameter names +-------------------------- + +The following postscreen parameters replace names that contain 'blacklist' +or 'whitelist': + + postscreen_allowlist_interfaces + postscreen_denylist_action + postscreen_dnsbl_allowlist_threshold + +These new parameters have backwards-compatible default settings +that support the old parameter names, so that the name change should +not affect Postfix behavior. This means that existing management tools +that use the old parameter names should keep working as before. + +This compatibility safety net may break when some management tools +use the new parameter names, and some use the old names, such that +different tools will disagree on how Postfix works. + +Changes in logging +------------------ + +The following logging replaces forms that contain 'blacklist' or +'whitelist': + + postfix/postscreen[pid]: ALLOWLIST VETO [address]:port + postfix/postscreen[pid]: ALLOWLISTED [address]:port + postfix/postscreen[pid]: DENYLISTED [address]:port + +To avoid breaking logfile analysis tools, Postfix keeps logging the old +forms by default, as long as the compatibility_level parameter setting +is less than 3.6, and the respectful_logging parameter is not explicitly +configured. As a reminder, Postfix will log the following: + + postfix/postscreen[pid]: Using backwards-compatible default setting + respectful_logging=no for client [address]:port + +To keep logging the old form, make the setting "respectful_logging = +no" permanent in main.cf, for example: + + # postconf "respectful_logging = no" + # postfix reload + +To stop the reminder, configure the respectful_logging parameter to +"yes" or "no", or configure "compatibility_level = 3.6". + +Major changes - threaded bounces +-------------------------------- + +[Feature 20201205] Support for threaded bounces. This allows mail +readers to present a non-delivery, delayed delivery, or successful +delivery notification in the same email thread as the original +message. + +Unfortunately, this also makes it easy for users to mistakenly delete +the whole email thread (all related messages), instead of deleting +only the delivery status notification. + +To enable, specify "enable_threaded_bounces = yes". + +Other changes - smtpd_sasl_mechanism_list +----------------------------------------- + +[Feature 20200906] The smtpd_sasl_mechanism_list parameter (default: +!external, static:rest) prevents confusing errors when a SASL backend +announces EXTERNAL support which Postfix does not support. + +Other changes - delivery logging +-------------------------------- + +[Incompat 20200531] Postfix delivery agents now log an explicit record +when delegating delivery to a different Postfix delivery agent. + +For example, with "best_mx_transport = local", an SMTP delivery +agent will now log when a recipient will be delivered locally. This +makes the delegating delivery agent visible, where it would otherwise +have remained invisible, which would complicate troubleshooting. + + postfix/smtp[pid]: queueid: passing <recipient> to transport=local + +This will usually be followed by logging for an actual delivery: + + postfix/local[pid]: queueid: to=<recipient>, relay=local, ... + +Other examples: the local delivery agent will log a record that it +defers mailbox delivery through mailbox_transport or through +fallback_transport. + +Other changes - error logging +----------------------------- + +[Incompat 20200531] Postfix programs will now log "Application error" +instead of "Success" or "Unknown error: 0" when an operation fails with +errno == 0, i.e., the error originates from non-kernel code. + +Other changes - dns lookups +--------------------------- + +[Feature 20200509] The threadsafe resolver API (res_nxxx() calls) +is now the default, not because the API is threadsafe, but because +this is the API where new features are being added. + +To build old style, build with: + + make makefiles CCARGS="-DNO_RES_NCALLS..." + +This is the default for systems that are known not to support the +threadsafe resolver API. |