Hi
I am stuck on an issue.
When emails are sent to a particular domain they SOMETIMES get bounce backs saying the following:
Delivery to the following recipient failed permanently:
xxx@yyy.comTechnical details of permanent failure: Google tried to deliver your message, but it was rejected by the server for the recipient domainyyy.com bymail.yyy.com. [a.b.c.d].
The error that the other server returned was: 550 5.7.1 sender IP address has been blocked by SpamCop
However, they have been getting these bounce backs for any sender into the network from outside.
And none of the sender IP addresses are blocked by SpamCop. The issue also shows AbuseAt and Spamhaus saying the same thing and the sender IP address is not in their Blocked list either.
Also the receiver is not in the blocked list either.
Usually if I send an email that is blocked, if I resend it immediately, it gets through.
I can also send an email and it goes through without an issue first time.
The receiver has ESET Mail Security. I temporarily disable AntiSpam Protection and still got a bounce back.
Any Ideas what might be causing this?
Thanks