Postfix stable release 2.6.2 fixes one defect in SASL support.
This does not affect Postfix versions 2.5 and earlier.
With plaintext SMTP sessions AND smtpd_tls_auth_only=yes AND
smtp_sasl_auth_enable=yes, the SMTP server logged warnings for
reject_*_sender_login_mismatch, instead of enforcing them.
You can find Postfix version 2.6.2 at the mirrors listed at
http://www.postfix.org/
The same fix is also available in Postfix snapshot 2.7-20090528.
Postfix versions 2.5 and earlier are not affected.
Wietse