RE: open relay

[Carl Chipman <cchipman@xxxxxxxxxxxx>]

We could never fully secure Post.Office against open relay.  Eventually we had
to use another SMTP server which allows relay only to our system, unless you
authenticate and then it allows mail to relay to anywhere.

Carl Chipman


-----Original Message-----
From: Bruce Sommer [mailto:bes-tech1@xxxxxxxxxxxxxxxx]
Sent: Tuesday, January 28, 2003 11:47 PM
To: post_office@xxxxxxxxxxxxxxx
Subject: Re: open relay

You might want to remove the "local mail domain" option from the "External Relay
Restrictions" section.

>From section 4.5.1 of the Admin manual:

"When relay restrictions are set using domain names, Post.Office checks the
return address on the envelope of every message in the system against the list
of allowed or restricted domains. Because a user can easily alter his/her return
address to include any domain, using domains to restrict or allow relaying is
not as secure as restricting by IP addresses."

On 1/28/03 at 23:22 bob@xxxxxxxxxxxxx (Bob Minor) stated:

>I have inherited a tenon post.office system. osirusoft thinks its an
>open relay even though I chose "Restrict relay mail except these ip's
>and local domains ". Then I chose "and only if delivery is for local
>domains".
-----
Bruce Sommer
bes-tech1@xxxxxxxxxxxxxxxx
http://www.sommerfamily.org/~besommer/index.html

"SCSI is *NOT* magic.  There are *fundamental technical reasons* why it is
necessary to sacrifice a young goat to your SCSI chain now and then."
-- John Woods

Lifetime Member of JPFO <http://www.jpfo.org/>
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