Last Wednesday we upgraded our Smartermail system from v8.1.4212 to 9.1.4429. We've discovered that some incoming messages are not being delivered properly since the upgrade. Our email infrastructure is set up so that DNS MX records are set to deliver incoming emails to 3 Postfix servers running Linux or FreeBSD which do some simple checks to block the most blatantly obvious spams, do virus scans, and queue messages before delivering to Smartermail for fine-grained spam filtering and delivery to mailboxes. Since the upgrade, messages which Postfix identifies as being from MAILER-DAEMON are not being delivered properly. They are either being delayed or not delivered at all and just build up in the sending queue in Postfix. The logs on the Postfix side show the connection being attempted to deliver to the smartermail system, then times out after several minutes as shown below. Code: Mar 6 13:40:01 dnsmx1 postfix/qmgr: 868392E0B5: from=<>, size=73935, nrcpt=1 (queue active) Mar 6 13:42:01 dnsmx1 postfix/smtp: 868392E0B5: to=<email@example.com>, relay=samsahost02.samsa.com[22.214.171.124]:25, delay=110062, delays=109942/0.03/0.01/120, dsn=4.4.2, status=deferred (conversation with samsahost02.samsa.com[126.96.36.199] timed out while sending DATA command) On the Smartermail side I get this logged... Code: 13:39:53 [188.8.131.52] rsp: 220 samsahost02.samsa.com 13:39:53 [184.108.40.206] connected at 3/6/2012 1:39:53 PM 13:39:53 [220.127.116.11] cmd: EHLO mx1.samsa.com 13:39:53 [18.104.22.168] rsp: 250-samsahost02.samsa.com Hello [22.214.171.124] 250-SIZE 31457280 250-AUTH LOGIN CRAM-MD5 250 OK 13:39:53 [126.96.36.199] cmd: MAIL FROM:<> 13:39:53 [188.8.131.52] rsp: 250 OK <> Sender ok 13:39:53 [184.108.40.206] cmd: RCPT TO:<firstname.lastname@example.org> 13:39:53 [220.127.116.11] rsp: 250 OK <email@example.com> Recipient ok 13:39:53 [18.104.22.168] cmd: DATA 13:39:53 [22.214.171.124] Exception: Couldn't find a viable address at SmarterTools.Common.Text.EmailParser.GetEmailAddress(String s) at TcpServerLib.SMTPSession.#yDc(String ) 13:41:53 [126.96.36.199] disconnected at 3/6/2012 1:41:53 PM The exception is logged almost immediately then the connection appears to hang until it finally times out 2 or 3 minutes later. This system with the Postfix servers in front of the Smartermail server has been working since 2007 and nothing has changed on the Postfix side. It started the day of the Smartermail upgrade. Anyone have any ideas what might be happening to us? Thanks, Jeff Alles Network Administrator SAMSA, Inc.