Need help on this tricky problem.
- Email to domain XYZ.COM is first sent to an ISP that receives all email to this domain. Then their so called MailFeeder service sends all email (no filtering) to our mailserver which stands on local LAN with a firewall between.
- The mailserver is a Microsoft Exchange 2003 Server with Window Server 2003 Enterprise Server beneth. The server has Symantec Mail Security for Exchange as the primary virus and spam filtering software.
- Occasionally email sent to different recipients on our mailserver does not get thru. Senders get the following response:
(This response message is sent to the original sender from MAILER-DAEMON@nexus.tripnet.se, which is the ISPs mailfeed server).
"This message was created automatically by mail delivery software.
A message that you sent could not be delivered to all of its recipients.
The following adress (es) failed:
and then I sent the mail content
550 5.7.1 Requested action not taken: message refused"
The ISP says that this error is happening at our mailserver, and that our server is the problem. But I´ve checked the message tracking log and cannot find any outgoing error messages such as the one above, which indicates that the problem could be at the ISP.
Does anyone have any ideas?
Our mailserver is configured as recommended with dns servers, smtp settings etc in Exchange.