My exchange 2003 is having a spordaic problem for one user sending out bulk email. The message gets hung up in the queue with the error message Event ID 4006 MSExchange Transport unable to open message for delivery. All of the local users in our company recieve the message but none of the external teaming partners do. I can manually clear the queue, he has immediately resent the message and then it sends properly. This has happened once on a calender invite and once on just a regular message sent out to approximately 70 people.
I have completely verified that this is not a DNS issue. I have verified the the SMTP driver on the exchange server is running properly. All other mail is sending properly and we are recieving email fine. We are running symantec exchange edition on the server with premium antispam filtering enabled. I doubled checked to ensure that heuristic diagnostic was turned off, which it was.
I came across and Microsoft KB article http://support.microsoft.com/kb/938650/en-us
but we are not getting this particular error message in the event logs.
The user in question is running Outllook 2007. He has been sending to this particular email list for several months without issue. The first time it happened was the beginning of last week. I cleared the queue thinking it was just a fluke. He sent out several bulk emails out yesterday and it happened again where one got hung up in the retry queue.
Error recorded in application event log
Event ID 4006 MSExchangeTransport
Message delivery to the host "<IP address>" failed while delivering to the remote domain "<domain name>" for the following reason: Unable to open the message for delivery.
I removed the real ip and domain name. And I can reach the domain names and Ip addresses throught telnet session.
Thanks for any assistance