Here is one for those who like a challenge.
I have had a very interesting issue come up today.
I can find no reason for this what so ever.
I have seen a number of posts about this and most all of them are around port 25 for an ISP - this is not the case. ***
My servers have been up and running for about 3 years
their serevers have been up and runnig for about 2 years.
email has in the past been sent AND received with no trouble.
reciently my email will not leave the queue for thier domain.
My Users can send / receive email from any domain / user
their users can send / recive form any domain / user
The ONLY thing that is not working on both domains is the ability for us to send them emails.
I know I have not changed anything on my end. My fellow minions claim to be guilt free. And the receiveing end says no changes on his end.
- error message -
541 4.4.0 Primary target IP address responded with: "421 4.2.1 Unable to connect." Attempted failover to alternate host, but that did not succeed. Either there are no alternate hosts, or delivery failed to all alternate hosts.
- checked MX / DNS records with MxToolBox.com -
Mine cam back clean his has an issue with
"Warning - reverse DNS does not match SMTP Banner" &
"Warning - Does not support TLS"
I can telnet to his server on port 25 and receive the proper responses from the exchange server ehlo command.
there are no 3rd party relay services.