Re: [exim] Call back and whitelisting

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Author: Brian Candler
Date:  
To: carinus.carelse
CC: exim-users
Subject: Re: [exim] Call back and whitelisting
On Thu, Mar 24, 2005 at 01:20:45PM +0200, carinus.carelse@??? wrote:
> Is it possile for exim to do a callback on the email address to the mail
> server and then reject if the mailserver doesn't know about the address
> and then to be able to whitelist addressess that give us problems.


Yep: in principle,

  deny
     ! < sender is in whitelist >
     ! < sender callback verification >


Tony Finch's ppswconf configuration does this, see his excellent paper at
http://www-uxsup.csx.cam.ac.uk/~fanf2/hermes/doc/talks/2005-02-eximconf/paper.html

He puts the logic in a sub-acl which is called from the main one; look for
"aux_verify_sender:"

The whitelist file is called nocallout.cdb, and he also uses
dsn.rfc-ignorant.org as a whitelist (i.e. domains which are *known* to
handle bounces wrongly, and therefore will fail callback verification). If
the address is not on either of those then a standard callback verify is
done.

Regards,

Brian.