E-mail Verification as a means of SPAM filtering

[pedromt]

Recently my boss has been on a kick of implementing an E-mail verification bounce-back as a means of SPAM filtering, despite my objections. Unfortunately, mailfoundry doesn't seem to have a method of doing this and so I've been looking at the few solutions I could find. They're all much more comprehensive than what our needs are since all the other services are provided by mailfoundry.

I was hoping someone might have a suggestion as to how I could implement something like this. Possibly for just two or three users since those three seem to attract 80% of the spam in this office.

Thanks.

[Kevin]

This is a really, really bad idea. Mail Foundry does not implement it, which is a good thing. A huge percentage of spam comes from "bogus" from addresses. These addresses are often randomly selected addresses from their spam lists, which means by using a verification service, you are generating unsolicited bounce messages to users that never sent anything to you. This tends to result in a small (1 - 2% or so) abuse complaint level for your mail server.

In addition to this being a generally obnoxious thing to do to users that didn't send the messages to you, it also means that your system will bounce messages back to spam traps that spammers have collected in their lists. The result: your email server will quickly and frequently appear on blacklists because you're emailing spam traps.

This problem exists for autoresponders (which is why we no longer offer autoresponders on shared hosting) and for any server which accepts mail temporarily and bounces it later. The proper solution is to only generate bounce type messages or autoresponses for emails you are rather sure are not spam and to make sure your server rejects messages with 400 or 500 error codes if at all possible, rather than accepting the messages and bouncing later.

I can't recommend any software that does what you want, but it's mainly because I've never looked for any and I would have to consider any software I found to be horrible due to the above comments. :)