An on-line version of this announcement is available at http://www.postfix.org/announcements/postfix-2.6.5.html
The stable release Postfix 2.6.5 addresses the defects described below (some already addressed with the not-announced Postfix 2.6.3 release). These defects are also addressed in the legacy releases that are still maintained: Postfix 2.5.9, 2.4.13 and 2.3.19.
Do not use Postfix 2.6.4, 2.5.8, 2.4.12, 2.3.18, 2.7-20090807, and 2.7-20090807-nonprod. These contain a DNS workaround that causes more trouble than it prevents. It is removed until further notice.
Defects fixed with Postfix 2.6.3:
The Postfix Milter client got out of step with a Milter application after the application sent a "quarantine" request at end-of-message time. The Milter application would still be in the end-of-message state, while Postfix would already be working on the next SMTP event, typically, QUIT or MAIL FROM. In the latter case, Milter responses for the previously-received email message would be applied towards the next MAIL FROM transaction. This problem was diagnosed with help from Alban Deniz.
Defects fixed with Postfix 2.6.5:
The Postfix SMTP server would abort with an "unexpected lookup table" error when an SMTPD policy server was mis-configured in a particular way.
The source code is available from ftp://ftp.porcupine.org/mirrors/postfix-release/index.html and from the mirrors listed at http://www.postfix.org/download.html.