I need to do the following with Postfix: when receiving mail from remote server, check sender IP with various blacklisting services (e.g. spamhaus or abuseipdb), but avoid rejecting mail automatically, because such services make mistakes sometimes. When IP is blacklisted, I need to add a header to the mail received, so I can later move it to Spam folder, but allow mail to come in.
I know that this can theoretically be done by writing my own milter that would analyze Received: headers, but that seems too complex.
Is there any simple and standard way or doing this? Maybe Postfix itself can do it somehow, or there already exists some milter software that can do this?
