I'm sorry but with respect you have made assumptions that are incorrect. I said nothing about a domain being used by spammers. I quite clearly said I have a server(s) that are constantly being pounded by people trying to get into accounts but using failed passwords and usernames. My question was not at all about spam. I specifically asked if the IP's of those trying to break into mail accounts are being added to fail2ban and if not how I could address it.As the domain was used by spammers some time, it may be blacklisted and that's why some filters block the email as spam. ... This time the emails passed through the filters and reached the recipients. So, if you find your emails blocked by the spam filters, it may be because of a domain name you use in the message content.