I am running Exchange 2003. The DNS server on this machine points to our internal DNS servers, running Windows 2000. The DNS servers have our ISP's DNS servers listed under the forwarders tab, and the 'do not allow recursion' box is not checked.
The problem I am having is that email message destined for an outside domain are smetimes being bounced the to senders. The message they receive is:
Subject: Underliverable: <original subject line>
Your message did not reach some or all of the intended recipients.
Sent: <Date time sent>
The following recipenat(s) could not be reached:
email@example.com on <datetime>
You do not have permission to send to this recipient. For assistance, contact your system administrator.
<mail.peachtreedata.com #5.7.1 smtp; 550 5.7.1 Unable to relay for <firstname.lastname@example.org>
I do not know is this is a DNS issue looking up the domain name to send the message to, or if for some reason the recipient domain mail server is rejecting our mail message. I do have reverse DNS pointer records for mail.peachtreedata.com setup.
If we resend the same message again, or maybe two or hree times, the message eventually goes through with no changes being made to to system setup.
Can anyone please help with this issue? It only happens on maybe 1 out of 100 messages being sent, but it is still a problem.