Hi all, I know that there are many similar topics in forum, but my problem is a bit different.
My environment : Exchange Server 2013 (Windows Server 2008 R2 Ent) , Domain Controller + DNS (Windows Server 2008 R2 Ent) . EX Server uses DC as preferred DNS Server .
Sometimes, I cannot send email to customers / people of some domains, I get error in my MS Outlook :
Delivery is delayed to these recipients or groups: cus1@customerdomain.com cus2@customerdomain.com Subject: ***** 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, 22 hours and 52 minutes. You'll be notified if the message can't be delivered by that time. Diagnostic information for administrators: Generating server: ex.mydomain.com cus1@customerdomain.com Remote Server returned '400 4.4.7 Message delayed' cus2@customerdomain.com Remote Server returned '400 4.4.7 Message delayed' Original message headers: ...
Then I open Exchange Toolbox ==> Queue Viewer, what I see about messages which are sent to customerdomain.com :
From Exchange Server command promt, I can query dns
nslookup Default Server: mydc.mydomain.com Address: 192.168.10.2> set type=mx> customerdomain.com Server: mydc.mydomain.com Address: 192.168.10.2 Non-authoritative answer: customerdomain.com MX preference = 0, mail exchanger = aspmx.l.google.com customerdomain.com MX preference = 5, mail exchanger = alt1.aspmx.l.google.com customerdomain.com MX preference = 5, mail exchanger = alt2.aspmx.l.google.com customerdomain.com MX preference = 10, mail exchanger = aspmx2.googleemail.com customerdomain.com MX preference = 10, mail exchanger = aspmx3.googleemail.com aspmx.l.google.com internet address = 74.125.200.27
I can telnet to their mx server port 25 (of course they use gmail hosting) and send email to someone@gmail.com normally.
It just happen sometimes, with some domain (I can send/receive email with customerdomain.com normally before).
How can I fix it ?