Dude, Where's My E-Mail? When Server-Side Spam Filters Go Wrong.

Recently I've seen first hand what happens when they get overzealous.

For no apparent reason - the outgoing email of a firm I worked with starting bouncing at their SMTP server. The server was responding with some esoteric error message.

I called support, which informed me they had tripped some sort of spam filter. Their own ISP thought they were a spammer!

The underlying issue turned out to be the DNS host info for our outgoing router. Apparently it didn't have a forward map. I've heard of not having a reverse map causing a problem - but usually not having a forward map isn't.

The DNS was controlled by a third party, which of course claimed there wasn't any real problem and nothing should be done.

The problem hasn't since re-occurred. My bet is they took a bunch of their customers email offline when they implemented this new policy, and have made a revision to their filtering setup.

I suspect these sorts of things are happen thousands of times daily causing the delay or loss of thousands of emails.

These types of issues aren't as problematic with a client-side spamfilter, since users can easily review and recover messages accidentally intercepted as spam. Problematic addresses can be added to whitelists.

SpamButcher's free mail filter download trial can be obtained from www.spambutcher.com. The trial works for 21-days before needing registration.

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