[Mimedefang] spf integration?

Miha Verlic @ domenca.si miha.verlic at domenca.si
Tue Jul 25 07:52:10 EDT 2006


Hello,

recently we've had some problems with blacklists because of 
autoresponders (vacations... ;). To prevent these kind of problems, I'd 
like to setup some kind of SPF checking and only allow autoreponses to 
email addresses that are most likely not fake.

I'm thinking of something like this:

1.) Check SPF record for domain - if it exists obbey this rule and add 
X-Tag respectively, let's say "X-SPF: Valid" or "X-SPF: Forged"
2.) If domain does not have SPF record, check it's MX records - if mail 
comes from any of the MXes, mark it "X-SPF: Looks real".
Is this test fails compare domain name with From: field, ie: if mail is 
from joe at example.com, it's valid if it comes from *.example.com.
If this is another test that fails, I'd like to have some whitelist CIDR 
ranges, which should label mail "X-SPF: whitelisted".
3.) All other mail should get "X-SPF: Forged" tag appended to headers.

And then with autoresponders (which are done via .procmailrc), I could 
simply ignore any mail that comes with "X-SPF: Forged" tag attached.

Any ideas if - or better yet - how can this be accomplished with 
mimedefang? I'm also interested in comments about above "solution".

I'm also thinking that somewhere in (near?) future maybe I could also 
use this feature to block some spam that is most obviously forged. At 
least for the domains that have a valid SPF record.

Thanks
-- 
Miha Verlic
Sysadmin

Domenca d.o.o.
Tel.: +386 4 5835449
Fax.: +386 4 5831999
www.domenca.com



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