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Re: spf record

Marek Podmaka wrote:

  Interesting discussion about SPF... There are actually 2 things to
  think about - one is implementing SPF on DNS for our domains and the
  other is using SPF to limit "bad" incoming mail. In my opinion the
  second one has only advantages. So I would like to ask what do you
  recommend? Integrate it in postfix somehow? Or is it enough to turn
  on SPF checking in SpamAssassin? How?
My first reaction would be that implementing it in your SMTP server would only be useful if you were going to reject/bounce stuff on SPF failures regardless of content.
Like I mentioned earlier, I think that the strong point of SPF is that it lets you trust your domain-name-based RBL's more. IIRC, SpamAssassin 3 already checks SPF by default (you have to have the Mail::SPF::Query perl package on your machine)... but it just doesn't assign any scoring to SPF failures or successes.
You can change the scoring by either editing the system-wide spamassassin.conf file or by editing the per-user $HOME/.spamassassin/user_prefs. The syntax for adjusting scoring is here: 
http://spamassassin.apache.org/full/3.0.x/dist/doc/Mail_SpamAssassin_Conf.html#scoring_options

In short, you'd use something like:

   score SYMBOLIC_TEST_NAME n.nn
where SYMBOLIC_TEST_NAME is the name of one of SpamAssassin's test conclusions. For SPF, these would include: 
SPF_FAIL           SPF: sender does not match SPF record (fail)
SPF_HELO_FAIL       SPF: HELO does not match SPF record (fail)
SPF_HELO_NEUTRAL       SPF: HELO does not match SPF record (neutral)
SPF_HELO_PASS       SPF: HELO matches SPF record
SPF_HELO_SOFTFAIL       SPF: HELO does not match SPF record (softfail)
SPF_NEUTRAL       SPF: sender does not match SPF record (neutral)
SPF_PASS       SPF: sender matches SPF record
SPF_SOFTFAIL       SPF: sender does not match SPF record (softfail)
and "n.nn" is the amount to increase or decrease the spam score of the message.
Personally, I'd use the scoring adjustments to increase the score of SPF failures and then bump up the scores of RBL results. 

- Joe**

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