|Think about Loose Coupling|
Re: Just Another Discussion of Spamby BazB (Priest)
|on Mar 17, 2005 at 21:18 UTC||Need Help??|
There are a number of problems with your idea: the first one being that spammers regularly forge From: addresses.
SMTP does support VRFY (verify) and EXPN (expand) commands to check that a given account exists on a machine, however this has long since been disabled by most administrators (myself included) ever since spammers started abusing the system to identify and harvest valid accounts. Have a read of RFC2821 - SMTP
An alternative would be to try and send a test message to the accounts, but you'd be effectively spamming too.
Even if you could verify the existence of an address, would you really want to delete all messages from an email address that no longer exists?
Spam Assassin does a pretty good job of filtering spam - I'd recommend using that (or an alternative tool), rather than your fairly coarse criteria.
If the information in this post is inaccurate, or just plain wrong, don't just downvote - please post explaining what's wrong.