The stable Postfix release is called postfix-2.3.x where 2=major release number, 3=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-2.4-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. Incompatibility with Postfix 2.2 and earlier ============================================ If you upgrade from Postfix 2.2 or earlier, read RELEASE_NOTES-2.3 before proceeding. Incompatible changes with Postfix snapshot 20061209 =================================================== The Postfix installation procedure no longer updates main.cf with "unknown_local_recipient_reject_code = 450". Four years after the introduction of mandatory recipient validation, this transitional tool is no longer neeed. After upgrading Postfix you MUST execute "postfix reload", otherwise the queue manager may log a warnings with: warning: connect to transport retry: Connection refused The upgrade procedure adds a new "retry" service to the master.cf file. If you make the mistake of copying old Postfix configuration files over the new files, the queue manager may log warnings with: warning: connect to transport retry: Connection refused To fix your master.cf file, use "postfix upgrade-configuration" followed by "postfix reload". Small changes were made to the default bounce message templates, to prevent HTML-aware software from hiding or removing the text "", and producing misleading text. Major changes with Postfix snapshot 20061209 ============================================ Better interoperability with non-conforming SMTP servers that reply and disconnect before Postfix has sent the complete message content. Improved worst-case (old and new) queue manager performance when deferring or bouncing large amounts of mail. Instead of talking to the bounce or defer service synchronously, this work is now done in the background by the error or retry service. Improved worst-case (new) queue manager performance when delivering multi-recipient mail. The queue manager now proactively reads recipients from the queue file, instead of waiting for the slowest deliveries to complete before reading in new recipients. This introduces two parameters: default_recipient_refill_limit (how many recipient slots to refill at a time) and default_recipient_refill_delay (how long to wait between refill operations). These two parameters act as defaults for optional per-transport settings. Incompatible changes with Postfix snapshot 20061006 =================================================== The format of SMTP server TLS session cache lookup keys has changed. The lookup key now includes the master.cf service name. Major changes with Postfix snapshot 20061006 ============================================ Individual CISCO PIX bug workarounds are now on/off configurable. This introduces new parameters: smtp_pix_workarounds (default: disable_esmtp, delay_dotcrlf) and smtp_pix_workaround_maps (workarounds indexed by server IP address). The default settings are backwards compatible. Incompatible changes with Postfix snapshot 20060806 =================================================== Postfix no longer announces its name in delivery status notifications. Users believe that Wietse provides a free help desk service that solves all their email problems.