Greetings!
We are an IT company offering various Internet related services.
Several customers complained about problems sending mail from our server to recipients on the messagelabs platform.
The problems are related only to one server, mx3.lynx2000.it (IP 176.31.116.222).
Other server such as mx1.lynx2000.it or mx2.lynx2000.it are not influenced.
The error messages are the same:
"refused to talk to me: 501 Connection rejected by policy [7.7] 20114, please visit www.messagelabs.com/support for more details about this error message."
Some example domains showing the problem are the following:
ferrarigiorgio.it
idrobios.com
resinchim.com
We have checked the mail servers, and they have no evidence of problem:
- none of them is in blacklist (checked with mxtoolbox.com)
- none of them is in Symantec blacklist (ipremoval.sms.symantec.com/lookup/)
- all of them have good reputation in talosintelligence.com
- all of them have an updated antivirus
- we checked logfiles and there are no strange behaviour
This is very inconvenient for us as we will need to contact all of these domains. It is not a practical practice at all.
I would appreciate if anyone could shed some light to this matter.
Thank you very much for your cooperation.