Bugfix (introduced: 2001): qmqpd null pointer bug when it
logs a lost connection while not in a mail transaction.
Reported by Michal Adamek. File: qmqpd/qmqpd.c.

Bugfix (introduced: 20080212): incorrect client name in
reject messages from check_reverse_client_hostname_access
and check_reverse_client_hostname_{mx,ns}_access.  They
replied with the verified client name, instead of the name
that was rejected.  Problem reported by Reindl Harald. File:
smtpd/smtpd_check.c.

Bugfix (introduced: Postfix 2.3): the PREPEND access/policy
action added headers ABOVE Postfix's own Received: header,
exposing Postfix's own Received: header to Milters (protocol
violation) and hiding the PREPENDed header from Milters.
The latter caused problems for DMARC implementations with
SPF policy plus DKIM Milter.  PREPENDed headers are now
added BELOW Postfix's own Received: header and remain visible
to Milters. File: smtpd/smtpd.c.

Bugfix (introduced: Postfix 2.3): when a Milter inserted a
header ABOVE Postfix's own Received: header, Postfix would
expose its own Received: header to Milters (violating
protocol) and hide the Milter-inserted header from Milters
(wtf).  Files: cleanup/cleanup.h, cleanup/cleanup_message.c,
cleanup/cleanup_state.c, milter/milter.[hc], milter/milter8.c.

Cleanup: revert the workaround that places headers inserted
with PREPEND actions or policy requests BELOW Postfix's own
Received: message header. File: smtpd/smtpd.c.