Re: Stopping Frequently Forged Domains

From: Scott Lambert (no email)
Date: Mon Jun 03 2002 - 13:11:29 EDT


On Sun, Jun 02, 2002 at 11:16:49PM -0600, Robert Dalton wrote:
> Stavros Patiniotis wrote:
> >
> >Won't this break your mail for the case in which one of your backup relays
> >is delivering the mail to you?
>
> add your mx backup to this file.
>
> /etc/postfix/strict_client_map:
> yahoo.com OK
> hotmail.com OK
> friendly.com OK
> mxbackup.mydomain.com OK

Actually, I think the smtpd_recipient_restrictions rules should
be ordered such that your MX's are permitted before any other
restrictions. I would expect most MX's to be included in the
$mynetworks list. You also want pop-before-smtp access lists to be
checked before the strict_client_map restrictions.

Something like the following seems to work. I got all of this from
Ralph Hildebrandt and others on this list. It also has the benefit
of holding off on most of the DNS lookup checks as long as possible.

smtpd_recipient_restrictions =
   permit_mynetworks
   check_client_access hash:$config_directory/pb4s
   reject_unauth_destination
   check_recipient_access hash:$config_directory/recipient_access
   check_client_access hash:$config_directory/blacklist
   reject_non_fqdn_sender
   reject_unknown_sender_domain
   reject_unknown_recipient_domain
   check_sender_access hash:$config_directory/freemail_access
   reject_maps_rbl
   permit

-- 
Scott Lambert                    KC5MLE                       Unix SysAdmin
      
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