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A few days ago I figured out that someone was trying to get access to my mailserver, obviously to send spam emails through.
After some research I found out that the sender uses a domain, refering to my server. Like you bind your domain to a static ip-adress, so this person did.
What I want to know is: Is there any way to block any traffic (IN/OUT) from that specific domain only? I really can't block my own ip, that's clear. I tried a few examples obtained from google where some people blocked whole domains by their names. Unfortunately (and even after cleaning my browsers cache) I still will be redirected to my own server.
Any suggestions?
Thanks in advance