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War on Spam
4/20/2004
By Simbey

Much of my free time lately has been devoted to my E-Mail server.  I have been setting up code for hunting out one last bug in the SMTP side of the program.  One remains that crashes the SMTP thread for a reason I cannot find.  The server will run for weeks at a time, and then suddenly, it crashes!  Fortunately the POP3 thread continues running!

My efforts are proving worthwhile so far.  The server is becoming stronger everytime I work on it.  Some of my debugging has also revealed that I am stopping spam before it reaches my inbox!

Take a look at these debug logs from SMTP sessions:

04-18-2004 11:50:02 - HELO adsl-65-64-51-142.dsl.tulsok.swbell.net
04-18-2004 11:50:02 - MAIL FROM: <ggaber@121pops.biz>
04-18-2004 11:50:02 - RCPT TO: <sales@simbey.com>
04-18-2004 11:50:02 - QUIT

04-19-2004 06:23:40 - EHLO simbey.com

04-20-2004 01:19:57 - HELO 64.173.195.210
04-20-2004 01:19:57 - MAIL FROM: <jyllharnn@weekonline.com>
04-20-2004 01:19:58 - RCPT TO: <simbey@simbey.com>

The first session only shows that there is no sales@simbey.com address, but what's interesting about this is that spammers attempt sales@domain attacks continually!  And they don't just try @simbey.com!

On a similar note, most sessions aren't attempts to spam local inboxes at all but are rather attempts to use my server as a relay point.  Obviously, all such sessions are shot down.

The second session failed because it tried to pass itself along as me...  After EHLO, the session was terminated by my server; I closed the socket!  Now I know what follows HELO/EHLO is trivial, but if spammers are really going to try and impersonate the recipient server so boldly, then at least that's an easy way to identify them!

The third session failed for a similar reason.  Actually, 64.173.195.210 IS Simbey.com, but that wasn't why the spammer failed.  I setup options for users to block any mail sent to them when the sender identified himself with an IP address in the HELO/EHLO message.  That's just laziness.  If "jyllharnn@weekonline.com" couldn't even think of a host to impersonate, then I know I'm glad I didn't have to bother deleting his junk!

A lot of spam is still getting through.  They found my new E-Mail address a couple weeks ago, and it's very frustrating receiving their crap, but I'm confident I'll figure something out to block even more.  Unfortunately, with every feature I write up as a possible fix for spam, I am closing quickly on the limits on the SMTP protocol itself.

I believe that for spam to be ended, a new protocol will need to be devised.  This may shock some of you, but I have decided to support any protocol that charges money to send E-Mail.

There are several options for spam out there, but I think charging a penny or even less per E-Mail is a certain solution.  I believe the most effective way to charge per E-Mail would be for the recipient's SMTP server to charge the sender rather than for the sender's SMTP server to charge the sender.  That would also avoid payment confusion among relay servers in between.

Now it's just a matter of HOW do we charge the sender!

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