[An on-line version of this announcement will be available at http://www.postfix.org/announcements/postfix-2.9.0.html]
Postfix stable release 2.9.0 is available. The main changes in no particular order are:
Support for long, non-repeating, queue IDs (queue file names). The main benefit of non-repeating names is simpler logfile analysis. See the description of "enable_long_queue_ids" in postconf(5) for details.
Memcache client support, and support to share postscreen(8) and verify(8) caches via the proxymap server. Details about memcache support are in memcache_table(5) and MEMCACHE_README.
Gradual degradation: if a database is unavailable (can't open, most read or write errors) a Postfix daemon will log a warning and continue providing the services that don't depend on that table, instead of immediately terminating with a fatal error. To terminate immediately when a database file can't be opened, specify "daemon_table_open_error_is_fatal = yes".
Revised postconf(1) command. It warns about unused parameter name=value settings in main.cf or master.cf (likely mistakes), understands "dynamic" parameter names such as names that depend on the name of a master.cf entry (finally, "postconf -n" shows all parameter settings), and it can display main.cf and master.cf in a more user-friendly format (postconf -nf, postconf -Mf).
Read/write deadline support in the SMTP client and server to defend against application-level DOS attacks that very slowly write or read data one byte at a time.
You can find the updated Postfix source code at the mirrors listed at http://www.postfix.org/.