For some time now, one of my private e-mail accounts has been getting flooded with
spam. I host my own e-mail server, so it's up to me to take action against the spammers.
My first inclination was to revert to a piece of software I've used in the past,
MailWasher. MailWasher is awesome, allowing me to view each e-mail at my convenience and choose whether to let it through or to delete it and/or bounce it back to the sender. It not only communicates with the public blacklist servers to identify known spam, but it also has its own intelligent spam detection for sniffing out the spam that may be coming from elsewhere. It even tells me if it's known spam or possible (or probable) spam.
But, it seems as though the amount of spam I've been receiving has been continuing to increase. This is extremely frustrating for me, 'cause while MailWasher will still correctly identify 99.9% of the known spam, it has to use my home Internet's bandwidth to contact my mail server to bounce e-mail, revealing a valid e-mail address in the process.
The solution: installation of a spam filter on my mail server. This spam filter is very simple. It will check the IP and/or e-mail address of the sender against public blacklist databases. If one of those databases says the sender is a spammer, the mail server immediately tells the sender that it's not allowed to deliver mail here. What that means is that any and all known spammers get stopped BEFORE their message comes anywhere near my inbox. In fact, it won't even let them get to the point of verifying the destination e-mail address (my mail server enforces the requirement of a valid destination address).
This should block about 80% of the spam I've been getting. I'll leave MailWasher to handle the remaining "unknown" spam.