Hello, I set up a new 2008 Forest with Exchange 2010. Internal mail is flowing perfectly. Sending mail to external address also works fine. But I just changed MX records to point to MXlogic where the mail is filtered. From there, I point the mail to my edge server. I can see external mail hitting the Edge server, but it never makes it to the mailbox. External users are getting a bounce something like this: Delivery is delayed to these recipients or groups: test@domain.com Subject: Test external This message hasn't been delivered yet. Delivery will continue to be attempted. The server will keep trying to deliver this message for the next 1 days, 19 hours and 57 minutes. You'll be notified if the message can't be delivered by that time. Reporting-MTA: dns;domain.local Received-From-MTA: dns;p01c11m117.mxlogic.net Arrival-Date: Fri, 17 Dec 2010 23:19:17 +0000 Final-Recipient: rfc822;test@domain.com Action: delayed Status: 4.4.7 Diagnostic-Code: smtp;400 4.4.7 Message delayed Will-Retry-Until: Sun, 19 Dec 2010 18:19:17 -0500 X-Display-Name: test@domain.com Why is my mail getting delayed and not going to the mailboxes? I need help! Thanks!

So the messages are queuing on the Edge Server? Whats the error message in the queues? Can the Edge Server connect on port 25 to the hub transports?Can you run the Mail Flow Troubleshooter in the EMC toolbox on the Edge Server? Check the message tracking logs? Run ExBpa? Edge server corectly configured and subscribed?

I see in the queue this error: 451 4.4.0 Primary target IP responded with "421 4.2.1 Unable to connect" Attempted to fail over to alternate host, but that did not succeed. Either there is no alternate hosts, or delivery failed to all alternate hosts. I can ping and resolve Hub fine. When I telnet from Edge to Hub, on port 25, the connection fails. FYI: Edge is in the DMZ. I will check the Mailflow Troubleshooter again, but I belive I got no errors last time. As far as I can tell the subscriptions are active and working. Like I said, internal and sending external mail works fine. Continuing to dig....

If you cant telnet on port 25 from the Edge to the Hub, thats the place to start :) Check the firewall, ensure it allows traffic on port 25 from the Edge to the HT. If it does, then check if the firewall supports any SMTP inspection logic ( Cisco are notorious for that) and disable.

Port 25 was not open from the Edge to the Hub through the DMZ. That was the problem. As soon as it was allowed through the firewall, all the queued mail went through. I got stuck because port 25 was open from the other direction, so mail was able to be sent out. Had to talk to our network guys to get it opened up both ways. Thanks!

Hi I was faced this issue ,ITs ISP related . If you have another Internet link change it than try.