libSPF spfmilter - SPF mail filter module
 
This milter is a fork of Jef Poskanzer's 'spfmilter' freely available for
download in its original from at http://www.acme.com/jef/  You can reach
Jef via Email: jef@acme.com.

Jef was kind enough to make his milter work with libSPF and for this I 
thank him!  Due to the amount of bloat in the spfmilter required to 
facilitate use of libspf-alt I have opted to FORK the spfmilter and remove
all of the fat.
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Sendmail includes a facility for plugging in custom mail filters,
called milters.  It's documented here: http://www.milter.org/milter_api/
Spfmilter implements the Sender Policy Framework (http://spf.pobox.com/)
as a milter, using the libspf library.

The idea of SPF is to prevent email forgery.  Each participating
site sets up a little definition of which hosts are allowed to send
mail claiming to be from that site.  When another site receives
mail, it checks the permitted-senders definition for the originating
site.  If the check fails, the mail is rejected.

Setting up the permitted-senders definition is very easy, you go
to the SPF Wizard at http://spf.pobox.com/wizard.html and fill out
a little form, then put the resulting string into your DNS records.
This milter implements the second half of SPF, checking the mail
you receive against other sites' SPF records.

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See the manual entry for more details.

I have integrated this 'spfmilter' as part of libSPF as a fork of the
milter.  I will continue to update it as Jef adds to the milter or 
perhaps he will even do this himself.

- James Couzens <jcouzens@codeshare.ca>

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