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One message for multiple recipients of the same domain

From: Alain D. (ML) (ad.mailingtiscali.be)
Date: Mon Jun 06 2005 - 14:06:38 CDT

Hi there,

I have a small question.

We recently setup a postfix/spamassassin mail relay acting as a front-end
mail relay. Here is the setup :

ANTISPAMHOST (postfix/spamassassin) ---> NEXTHOST (postfix/antivirus) --->
internal exchange server

ANTISPAMHOST is the internet MX for myincommingdomain.com.

My question is :

When an email arrives for TWO users of the SAME myincommingdomain.com, it
arrives in ONE smtp transaction on ANTISPAMHOST, ONE email. But after that,
TWO email messages are generated and sent to NEXTHOST. This is not optimal
as this means on NEXTHOST two mails are scanned for viruses despite it is
the same message. If my explanation is not clear please look at those logs
showing that one message becomes two messages.

So, how can I avoid that ? On ANTISPAMHOST the postfix configuration is
simple, in particular I have "relay_host=NEXTHOST".

Jun 2 20:08:44 ANTISPAMHOST postfix/smtpd[27045]: connect from
213-193-176-133.adsl.easynet.be[213.193.176.133]
Jun 2 20:08:44 ANTISPAMHOST postfix/smtpd[27045]: 73691166982:
client=213-193-176-133.adsl.easynet.be[213.193.176.133]
Jun 2 20:08:44 ANTISPAMHOST postfix/cleanup[27062]: 73691166982:
message-id=<20050602180844.73691166982ANTISPAMHOST.myincommingdomain.com>
Jun 2 20:08:44 ANTISPAMHOST postfix/nqmgr[12742]: 73691166982:
from=<sendersomedomain.com>, size=415, nrcpt=2 (queue active)
Jun 2 20:08:44 ANTISPAMHOST spamd[21607]: connection from ANTISPAMHOST
[127.0.0.1] at port 60378
Jun 2 20:08:44 ANTISPAMHOST spamd[21607]: processing message
<20050602180844.73691166982ANTISPAMHOST.myincommingdomain.com> for
nobody:501.
Jun 2 20:08:44 ANTISPAMHOST postfix/smtpd[27045]: disconnect from
213-193-176-133.adsl.easynet.be[213.193.176.133]
Jun 2 20:08:46 ANTISPAMHOST spamd[21607]: clean message (-97.0/5.0) for
nobody:501 in 1.8 seconds, 405 bytes.
Jun 2 20:08:46 ANTISPAMHOST spamd[21607]: result: . -96 -
BAYES_50,MSGID_FROM_MTA_ID,NO_REAL_NAME,UNDISC_RECIPS,USER_IN_WHITELIST
scantime=1.8,size=405,mid=<20050602180844.73691166982ANTISPAMHOST.myincommi
ngdomain.com>,bayes=0.499951408624623,autolearn=no
Jun 2 20:08:46 ANTISPAMHOST postfix/pickup[27283]: 6E60C166983: uid=99
from=<sendersomedomain.com>
Jun 2 20:08:46 ANTISPAMHOST postfix/cleanup[26808]: 6E60C166983:
message-id=<20050602180844.73691166982ANTISPAMHOST.myincommingdomain.com>
Jun 2 20:08:46 ANTISPAMHOST postfix/pipe[27107]: 73691166982:
to=<user-Amyincommingdomain.com>, relay=spamassassin, delay=2, status=sent
(ANTISPAMHOST.myincommingdomain.com)
Jun 2 20:08:46 ANTISPAMHOST postfix/pipe[27107]: 73691166982:
to=<user-Bmyincommingdomain.com>, relay=spamassassin, delay=2, status=sent
(ANTISPAMHOST.myincommingdomain.com)
Jun 2 20:08:46 ANTISPAMHOST postfix/nqmgr[12742]: 6E60C166983:
from=<sendersomedomain.com>, size=777, nrcpt=2 (queue active)
Jun 2 20:08:46 ANTISPAMHOST postfix/smtp[26838]: 6E60C166983:
to=<user-Bmyincommingdomain.com>,
relay=NEXTHOST.myincommingdomain.com[123.123.123.123],
delay=0, status=sent (250 Ok: queued as B76A983564)
Jun 2 20:08:46 ANTISPAMHOST postfix/smtp[26838]: 6E60C166983:
to=<user-Amyincommingdomain.com>,
relay=NEXTHOST.myincommingdomain.com[123.123.123.123],
delay=0, status=sent (250 Ok: queued as B76A983564)

Thanks for your help !

Kind regards
Alain