My organization runs two SIMS servers--one is a primary mail server; the second is 
purely a secondary mx (located in another city). The addition of the secondary mx is 
relatively recent and led to an unforeseen problem.

Last night, the primary mail server went down. As expected, mail for mprinc.com was 
instead delivered to mx2.mprinc.com. However, when mprinc.com was rebooted this 
morning, it started to reject mail from mx2.mprinc.com. Examination of the logs 
revealed that mx2.mprinc.com had been tempbanned by SIMS because of several messages 
addressed to persons who are no longer employed. Since all those messages were being 
delivered by mx2.mprinc.com, mprinc.com decided that mx2.mprinc.com was engaged in 
address harvesting.

Until now, I had deliberately left mx2's ip address out of the client hosts range for 
SIMS on mprinc.com. The logic was that all mail from mx2.mprinc.com should be for 
local addresses or router entries on mprinc.com; therefore, mprinc.com should not 
relay mail from mx2.mprinc.com. The goal was to prevent multihop relays.

However, in response to the problem this morning, I have added mx2.mprinc.com's ip 
address to mprinc.com's client hosts. Testing seems to indicate that this makes 
mx2.mprinc.com immune to tempbanning. Also, I have attempted to send mail through a 
multihop relay by addressing it to [EMAIL PROTECTED] and this was rejected by mx2 with 
the standard "relaying is not allowed" message.

1. Am I correct that by adding an IP address to the clients list, it becomes immune to 
tempbanning?
2. Am I correct that SIMS will refuse to attempt a multihop relay even if there is a 
.smtp entry in the router?

Also, while this isn't relevant to my configuration, how would you deal with this 
interaction if your backup mx didn't categorically reject multihop relays? It seems 
you couldn't safely put the backup mx into your clients list; instead you would have 
to create an "Unknown" account with a custom auto-reply. Would that be an appropriate 
technique?

Thank you.

Elliot Wilen
Network Administrator
Postmaster
MPR Associates, Inc.
Berkeley, CA


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