We've got a C350 installed at an ISP customer and recently, they've started to experience some major mail receiving problems with a specific domain(one of their major partners).
Connections are lost and some even get the 501 5.5.4 Invalid Address Error.
The Partner is using MS Exchange and using a WiMax connection to the ISP.
Exchange is sending mail directly and the mail is going through a PIX for Wimax customers and then going through ISP PIX before entering the C350.
SMTP Fixup turned off on both PIX.
See below, most of the time, the connection is initiated but after 20-50 minutes, the connection is lost. I've configured the timeout to 1 hour on IronPort:
22 Jun 2008 12:08:32 (GMT +0400) Message 1644287 on incoming connection (ICID 10308995) added recipient ([email protected])
22 Jun 2008 12:50:59 (GMT +0400) Incoming connection (ICID 10308995) lost.
22 Jun 2008 12:50:59 (GMT +0400) Message 1644287 aborted: Receiving aborted
501 5.5.4 Invalid Address, when mails are sent from the partner to ISP client.
Can you please help me on this?
Is there a timeout settings on the PIX which could be causing this problem?
Note that the partner can send mails to anywhere else and no problem. Same for the ISP.