[Mimedefang] Rejecting Some Recipients in filter_recipient() for Relay

imacat imacat at mail.imacat.idv.tw
Fri Mar 23 05:56:59 EST 2007


Dear all,

    Hi.  This is imacat from Taiwan.  I wonder if anyone has encounter
the same problem, or if this is already a known issue.  I have searched
the list archive with no result.  Sorry if I have missed something.

    I'm running MIMEDefang 2.61 on our mail gateway.  Since I have a way
to check against the intranet local recipients list, I would like to
reject the non-existing users there, preventing mailbox probe and
bandwidth loss and non-sense bounce.  So, I followed the illustration in
mimedefang-filter(5), created a subroutine filter_recipient() and check
the recipients there.  Everything work as expected, except for one thing.

    When the client is sending to multiple recipients, say:

delabsd at pristine.com.tw
imacat at pristine.com.tw
iamcat at pristine.com.tw
postmaster at pristine.com.tw

    I accept the first and reject the other 2.  The client did gots the
proper rejection SMTP message, too.

220 gate.pristine.com.tw ESMTP Sendmail 8.14.0/8.14.0; Fri, 23 Mar 2007 16:13:19 +0800
EHLO gate.pristine.com.tw
250-gate.pristine.com.tw Hello atlas.pristine.com.tw [10.0.0.125], pleased to meet you
MAIL FROM:<imacat at pristine.com.tw>
250 2.1.0 <imacat at pristine.com.tw>... Sender ok
RCPT TO:<delabsd at pristine.com.tw>
550 5.1.1 <delabsd at pristine.com.tw>... User unknown
RCPT TO:<imacat at pristine.com.tw>
250 2.1.5 <imacat at pristine.com.tw>... Recipient ok
RCPT TO:<iamcat at pristine.com.tw>
550 5.1.1 <iamcat at pristine.com.tw>... User unknown
RCPT TO:<postmaster at pristine.com.tw>
250 2.1.5 <postmaster at pristine.com.tw>... Recipient ok
DATA
354 Enter mail, end with "." on a line by itself
....
QUIT
221 2.0.0 gate.pristine.com.tw closing connection

    However, in the maillog, I found that 

Mar 23 16:13:19 gate sendmail[3964]: l2N8DJSR003964: Milter: to=<delabsd at pristine.com.tw>, reject=550 5.1.1 User unknown
Mar 23 16:13:19 gate sendmail[3964]: l2N8DJSR003964: Milter: to=<iamcat at pristine.com.tw>, reject=550 5.1.1 User unknown
Mar 23 16:13:19 gate sendmail[3964]: l2N8DJSR003964: from=<imacat at pristine.com.tw>, size=100, class=0, nrcpts=4, msgid=<200703230813.l2N8DJSR003964 at gate.pristine.com.tw>, proto=ESMTP, daemon=MTA, relay=atlas.pristine.com.tw [10.0.0.125]
Mar 23 16:13:19 gate sendmail[3964]: l2N8DJSR003964: Milter add: header: X-Scanned-By: MIMEDefang 2.61 on 10.10.0.101
Mar 23 16:13:26 mail sendmail[18859]: l2N8DPl9018859: <iamcat at pristine.com.tw>... User unknown
Mar 23 16:13:26 mail sendmail[18859]: l2N8DPl9018859: <delabsd at pristine.com.tw>... User unknown
Mar 23 16:13:26 gate sendmail[3967]: l2N8DJSR003964: to=<iamcat at pristine.com.tw>, delay=00:00:07, xdelay=00:00:07, mailer=relay, pri=210100, relay=mail.pristine.com.tw. [10.0.0.124], dsn=5.1.1, stat=User unknown
Mar 23 16:13:26 gate sendmail[3967]: l2N8DJSR003964: to=<delabsd at pristine.com.tw>, delay=00:00:07, xdelay=00:00:07, mailer=relay, pri=210100, relay=mail.pristine.com.tw. [10.0.0.124], dsn=5.1.1, stat=User unknown
Mar 23 16:13:27 mail sendmail[18859]: l2N8DPl9018859: from=<imacat at pristine.com.tw>, size=431, class=0, nrcpts=2, msgid=<200703230813.l2N8DJSR003964 at gate.pristine.com.tw>, proto=ESMTP, daemon=MTA, relay=gate.pristine.com.tw [10.10.0.101]
Mar 23 16:13:27 gate sendmail[3967]: l2N8DJSR003964: to=<imacat at pristine.com.tw>,<postmaster at pristine.com.tw>, delay=00:00:08, xdelay=00:00:08, mailer=relay, pri=210100, relay=mail.pristine.com.tw. [10.0.0.124], dsn=2.0.0, stat=Sent (l2N8DPl9018859 Message accepted for delivery)
Mar 23 16:13:27 gate sendmail[3967]: l2N8DJSR003964: l2N8DRSR003967: DSN: User unknown

    The gateway has rejected the 2 recipients, but it still ask the
intranet mail server for these 2 rejected recipients.  Why?

    I do not understand if this is a problem of MIMEDefang or the
Sendmail Milter library.  I looked into the MIMEDefang code and did not
find a clue.  Could anyone help me on this?

    Thank you in advance.

    The real problem to me is that:  When "gate" is rejected by "mail",
it tries to bounce to the spammer, which it should not.  Most spammer
envelop senders are faked.  This costs bandwidth and CPU and causes trouble
for the people being faked with.  Also if that mail cannot be bounce,
in case of non-edisting address, the postmaster, which is ME, is getting
the double-bounce.  Eventually I'm flooded by all theses non-sense
bounces and has little time on the real bounces that are warning me
about the network problems.  That's why I do not like it to contact the
intranet mail server.

-- 
imacat ^_*'
imacat at mail.imacat.idv.tw
PGP Key: http://www.imacat.idv.tw/me/pgpkey.txt

Tavern IMACAT's http://www.imacat.idv.tw/
Woman's Voice http://www.wov.idv.tw/
TLUG List Manager http://www.linux.org.tw/mailman/listinfo/tlug
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