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TmdaFingerprint

TMDA has an optional feature for applying a fingerprint to outgoing email. (See FINGERPRINT.) This only works if you use TMDA to manage all of your outbound email, either through tmda-sendmail or with tmda-ofmipd. This allows me to send email to myself without having to add myself in any of my whitelists. A common spam technique is to send the spam to and from the same address.

To get this to work, do the following:

  1. Set the FINGERPRINT variable in ~/.tmda/config. I use:
    FINGERPRINT = ["message-id", "from", "date"]
  2. Add a line to your incoming filter to check the fingerprint against incoming email. I use:
    pipe /usr/local/src/tmda/bin/tmda-fingerprint ok

There are a couple of odd things that don't work with this system:

  1. It always fails if you add "body" to FINGERPRINT. I don't know why
  2. WIth the above settings, and a completely empty body, it also always fails. Again, I don't know why.

Of course, a simpler way to handle this is described in theFAQ.

Here's the code for tmda-fingerprint


2007-02-24 17:18