I stood up an Exchange server (2003) 2 weeks ago. I only have 7 people including myself sending mail through as of right now while I test live. My company sends mail daily to a pop mail domain which we have been using for 5 years.
My Exchange will send mail to any domain we choose with the exception of this one domain we use the most.
What happens is, when a piece of mail is sent to this domain, it will go through fine. But once that first piece of mail gets to the Queues, the queue for that domain is created in the Queues Viewer. No more mail to that domain will clear that queue after that. They all just get stuck in there and sit until Exchange finally gives up and NDRs are created. Eventually I end up deleting those messages from the queue. After a while, the queue dissappears and the process begins again. The first piece of mail goes through, the queue is created, all mail from that point on gets stuck.
Again, this only happens with this one domain.
I have checked everything: DNS, MX, settings, ping, nslookup, telnet. I'm baffled. I'm also desparate. I have to get this fixed and I just cannot seem to be able to.
I do not use MTA/x400, I don't have any connectors, 3rd party software. My anti virus/spam has been checked by me and I called the vendor. I have checked with the hosting comapny I have my mx records with and my ISP.
I have no reason to think there is anything wrong with my local DNS on my DC. I have Exchange configured to use my ISP's external DNS as well.