There is one ISP that is rejecting mail from my mail server with the following error:
451 4.1.8 Possibly forged hostname for 220.127.116.11
My domain is mercedesshop.com.
Is there a problem with my mail server or is the issue with that ISP?
This is the definition I found for error 451 4.1.8:
"This means that it was able to resolve the IP address, but it doesn't resolve to a hostname that matches both forward and reverse lookups."
Please note that all of my incoming mail is routed through a proxy mail server to filter spam and viruses. I would not think that would make any difference for SMTP.