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Next: Unique Value Proposition Up: Technology behind SpamCheetah spam Previous: Contents Contents
Technical Summary
SpamCheetah does spam control in a fundamentally different way. Though greylisting has been around for a long time now it has not been implemented in tandem with other techinques and in a proper manner to extract maximum leverage.
This is what SpamCheetah attempts to do.
Here is a schematic to explain how SpamCheetah works.
The firewall that works in SpamCheetah redirects e-mail traffic depending on three parameters -
- sending IP address (From IP)
- envelope sender (who sends you mail?)
- envelope recipient (who is mail addressed to?)
If the above '3 tuple' are seen for the first time then the mail sender is subjected to the torturous SPAMD filtering (running on port 8025 above). There is a phenomenon called 'initial stuttering' that happens here. Instead of talking at full speed the MTA accepts mail one character at a time. This will piss off spammers and many go away. But legitimate senders have just one mail to send. Moreover they have to be RFC compliant. So they survive the test.
Once this process is completed, any subsequent mails from this sending IP address is assumed to be legitimate and they directly talk to the company mail server.
This in a nutshell is what my antispam solution does.
Next: Unique Value Proposition Up: Technology behind SpamCheetah spam Previous: Contents Contents Girish Venkatachalam 2009-08-09
