[Mimedefang] Should I try to doMIMEDefang withMailscanner forbackup MX

[Steve Campbell]

David,

----- Original Message ----- 
From: "David F. Skoll" <dfs at roaringpenguin.com>
To: <mimedefang at lists.roaringpenguin.com>
Sent: Tuesday, June 20, 2006 5:06 PM
Subject: Re: [Mimedefang] Should I try to doMIMEDefang withMailscanner 
forbackup MX


> Steve Campbell wrote:
>
>> I have two mailservers, and for the sake of simplicity, two domains. The
>> mailboxes for domain1 are on server1, and the mailboxes for domain2 are
>> on server2. Server2 is the backup MX for domain1, lower priority, higher
>> number. Server1 is the backup MX for domain2, lower priority, higher
>> number. Server1 relays to server2 for domain2. Server2 relays to server1
>> for domain1.
>
> OK; got it.
>
> [...]
>
>> I would like for MD to do the milter-ahead style stuff and only accept
>> mail for domain1 from server2 when server1 is inactive. Mail should be
>> going through the primary MX, not the secondary. So mail for domain1
>> that is sent to server2 would have to wait until MD determines whether
>> server1 is accepting mail or not and if it is for a valid user of
>> domain1. If server1 is accepting mail, drop the mail silently. If the
>> user is invalid, obviously drop the mail.
>
> Trust me: You don't want to do that.  If you do, you will have a 
> nightmarish
> time diagnosing what's going on.  server2 might think that server1 is up,
> when outside people really can't see server1.  Or server2 might think it's
> down when it really is up.
>
> Your best bet is to put the same spam-scanning rules on both servers,
> and have each server periodically synchronize its list of valid
> recipients to the other server.  (For example, you could store all the
> valid recipients in a Berkeley DB file and do a simple hash lookup in
> Perl to tell if the recipient is valid.)

Excellent idea! An MS Custom Function. Only problem, remember, is that I 
don't do Perl yet. But I hadn't thought of that way before. It would work. 
And I am learning Perl, and since I just wanted opinions, this may be the 
end of this thread.

Thanks very much!

Steve

>
> That way, each server can make its filtering decisions independently, and
> you don't have to rely on network connectivity or other conditions beyond
> your control to make accept/reject decisions.
>
> Regards,
>
> David.
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