This is the Postfix 3.10 stable release.

The stable Postfix release is called postfix-3.10.x where 3=major
release number, 10=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-3.11-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 3.8 or earlier, please read RELEASE_NOTES-3.9
before proceeding.

Dual license
------------

As of Postfix 3.2.5 this software is distributed with a dual license:
in addition to the historical IBM Public License (IPL) 1.0, it is
now also distributed with the more recent Eclipse Public License
(EPL) 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 - tls
-------------------

[Forward compatibility 20250212] Support for OpenSSL 3.5 post-quantum
cryptography. To manage algorithm selection, OpenSSL introduces new
TLS group syntax that Postfix will not attempt to imitate. Instead,
Postfix now allows the tls_eecdh_auto_curves and tls_ffdhe_auto_groups
parameter values to have an empty value. When both are set empty,
the algorithm selection can be managed through OpenSSL configuration.
For more, look for "Post-quantum" in the postconf(5) manpage.

[Feature 20250117] Support for the RFC 8689 "TLS-Required: no"
message header to request delivery of messages such as TLSRPT
summaries even if the preferred TLS security policy cannot be
enforced. This limits the Postfix SMTP client to "smtp_tls_security_level
= may" which does not authenticate server certificates and which
allows falling back to plaintext.

Support for the REQUIRETLS SMTP service extension remains future work.

[Feature 20240926] Support for the TLSRPT protocol (defined in RFC
8460). With this, a domain can publish a policy in DNS, and request
daily summary reports for successful and failed SMTP-over-TLS
connections to that domain's MX hosts.

Postfix supports TLSRPT summaries for DANE (built-in) and MTA-STS
(via an smtp_tls_policy_maps plugin). For details, see TLSRPT_README.

Major changes - privacy
-----------------------

[Feature 20250205] With "smtpd_hide_client_session = yes", the
Postfix SMTP server generates a Received: header without client
session info This setting may be used with the MUA submission
services (port 465 and 587), but it must not be used with the MTA
service (port 25).

Depending on the number of recipients, a redacted Received: header
has one of the following forms:

Received: by mail.example.com (Postfix) id postfix-queue-id
        for <user@example.com>; Day, dd Mon yyyy hh:mm:ss tz-offset (zone)

Received: by mail.example.com (Postfix) id postfix-queue-id
        Day, dd Mon yyyy hh:mm:ss tz-offset (zone)

The redacted form hides that a message was received with SMTP, and
therefore it does not need to provide the information required by
RFC 5321. It only has to satisfy RFC 5322.

Major changes - rfc2047
-----------------------

[Feature 20250105] Support for automatic RFC 2047 encoding of
non-ASCII "full name" information in Postfix-generated From: message
headers.  Encoding non-ASCII full names can avoid the need to use
SMTPUTF8, and therefore can avoid incompatibility with sites that
do not support SMTPUTF8.

The encoded result looks like "=?charset?Q?gibberish?=: for
quoted-printable encoding, or "=?charset?B?gibberish?=" for base64
encoding. Postfix uses quoted-printable for a full name that is
short or mostly ASCII, and uses base64 otherwise.

Background: when a message without a From: header is submitted with
the Postfix sendmail(1) command, Postfix may add a From: header and
use the sender's full name specified with the Postfix sendmail(1)
"-F" option, with the sendmail(1) "NAME" environment variable, or
with the GECOS field in the UNIX password database.

This introduces a new configuration parameter "full_name_encoding_charset"
(default: utf8) which specifies the character set of the full name
information in the Postfix sendmail(1) "-F" option or "NAME"
environment variable, or in the GECOS field in the UNIX password
database. The parameter value becomes part of the encoded full name,
and informs a Mail User Agent how to display the decoded gibberish.

Major changes - bugfix
----------------------

[Incompat 20241130] The spawn(8) daemon failed to enforce the command
time limit. It was sending the SIGKILL signal using the wrong
effective UID and GID. The pipe(8) daemon has always done this
right.

Major changes - database
------------------------

[Feature 20250207] When mysql: or pgsql: configuration specifies
a single host, assume that it is a load balancer and reconnect
immediately after a single failure, instead of failing all requests
for 60s.

[Feature 20250114] first/next iterator support for cdb: tables, and
other cdb: table code cleanups by Michael Tokarev.

[Feature 20241024] In a pgsql: client configuration, the setting
"dbname" is required, but ignored when the setting "hosts" contains
an URI with a database name.

[Feature 20241025] The Postfix pgsql: client configuration now
allows any well-formed URI prefix as a pgsql: client connection
target (the PostgreSQL URI parser decides what is allowed). The
dbname setting is now optional if the hosts setting specifies only
URIs.

Major changes - internal protocol
---------------------------------

[Incompat 20250116] Postfix needs "postfix reload" after upgrade,
because of a change in the delivery agent protocol. If this step
is skipped, Postfix delivery agents will log a warning:

    unexpected attribute smtputf8 from xxx socket (expecting: sendopts)

where xxx is the delivery agent service name.

Major changes - milter
----------------------

[Incompat 20250106] The logging of the Milter 'quarantine' action
has changed.  Instead of logging "milter triggers HOLD action", it
logs the reason given by a Milter application, or "default_action"
if a Milter application was unavailable and the milter_default_action
parameter or per-Milter "default_action" property specifies
"quarantine".

[Feature 20250106] The Postfix Milter implementation now logs the
reason for a 'quarantine' action, instead of "milter triggers HOLD
action".

- If the quarantine action was requested by a Milter application,
  Postfix will log the reason given by the application.

- If the quarantine action was requested with the "milter_default_action"
  parameter setting or with a per-Milter "default_action" property,
  Postfix will log "default_action".

Major changes - logging
-----------------------

[Feature 20250106] The Postfix Milter implementation now logs the
reason for a 'quarantine' action, instead of "milter triggers HOLD
action".

- If the quarantine action was requested by a Milter application,
  Postfix will log the reason given by the application.

- If the quarantine action was requested with the "milter_default_action"
  parameter setting or with a per-Milter "default_action" property,
  Postfix will log "default_action".

[Incompat 20250105] The SMTP server now logs the queue ID (or
"NOQUEUE") when a connection ends abnormally (timeout, lost connection,
or too many errors).

[Feature 20250105] The SMTP server now logs the queue ID (or
"NOQUEUE") when a connection ends abnormally (timeout, lost connection,
or too many errors).

[Incompat 20241104] The cleanup server now logs "queueid: canceled"
when a message transaction is started but not completed.

[Feature 20241104] The cleanup server now logs "queueid: canceled"
when a message transaction is started but not completed. This
provides a clear signal to logfile collation tools.

[Incompat 20241031] the Dovecot SASL client logging for "Invalid
authentication mechanism" now includes the name of that mechanism.

[Incompat 20241023] Postfix SMTP server 'reject' logging now shows
the sasl_method, sasl_username, and sasl_sender if available.
