RE: Mail Relaying

[Chris Bipes <chris.bipes@xxxxxxxxxxxxxxx>]

For these traveling users, set up a VPN server and give them the appropriate
VPN software.  Your mail server will see them as a local client.  Much MUCH
easier!  Also if you force only valid user to log on to your mail server for
sending out going mail, that should stop the relaying.

VPN is the easiest and most secure way.  Shut down the client ports and only
allow incoming e-mail to your domain in.

Christopher K. Bipes      mailto:ChrisB@Cross-Check.com
Operations & Network Mgr          mailto:Chris_Bipes@Yahoo.com
CrossCheck, Inc.          http://www.cross-check.com
6119 State Farm Drive     Phone: 707 586-0551 x 1102
Rohnert Park CA  94928    Fax: 707 586-1884

-----Original Message-----
From: Jon.Paris@hal.it [mailto:Jon.Paris@hal.it]
Sent: Thursday, April 12, 2001 2:19 PM
To: midrange-l@midrange.com
Subject: Mail Relaying


A prolonged period of frantic activity on our mail server (V4R4) last night
(80% + CPU!) led us to wonder if we were being used for relaying.  We
tested and sure enough we were wide open.  We have set things up as per
IBM's PTF cover letter on the subject but either I'm misunderstanding or I
have a problem with IBM's implementation.  I'm hoping someone can set me
straight.

In order to block relaying you either have to specify which IPs cannot
relay (not practical) or specify all those IPs which can.  This is the
approach we have used but there is a problem.  Several of our users travel
(me for one!) and often use e-mail from home or on the road.  I wouldn't
have thought connecting as an e-mail client counted as relaying but it
seems to.  Of course these users have a different IP each time they
connect.  In order to make it work the way I understand it, we'd have to
shut down the server - add the current IP and restart the server.  This
just isn't viable - so I'm hoping that I've missed something somewhere.

Can anyone enlighten me?
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