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Fox
Asked: 2013-07-23 10:54:38 +0800 CST

postfix/cleanup bad trivial-rewrite

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I use munin, the monitoring program, to alert me by email when something goes wrong on my server. It sends emails as munin.

Normally, when an email like this is to be delivered on the Internet, when postfix/cleanup is called, it asks trivial-rewrite to do a rewrite, which should append realdomain.tld to incomplete sender address.

It seams it does not, because my Postfix SMTP client then tries to send the email containing the From: munin@thehostname header, which Google doesn't really like:

Jul 22 10:00:15 thehostname postfix/pickup[3167]: 979BD1E447E: uid=110 from=<munin@thehostname>
Jul 22 10:00:15 thehostname postfix/cleanup[9609]: 979BD1E447E: message-id=<[email protected]>
Jul 22 10:00:15 thehostname postfix/qmgr[3276]: 979BD1E447E: from=<munin@thehostname>, size=454, nrcpt=1 (queue active)
Jul 22 10:00:16 thehostname postfix/smtp[9611]: 979BD1E447E: to=<[email protected]>, relay=ASPMX.L.GOOGLE.COM[173.194.67.27]:25, delay=0.49, delays=0.07/0/0.12/0.3, dsn=5.7.1, status=bounced (host ASPMX.L.GOOGLE.COM[173.194.67.27] said: 550-5.7.1 [9.8.7.6       1] Our system has detected an unusual rate of 550-5.7.1 unsolicited mail originating from your IP address. To protect our 550-5.7.1 users from spam, mail sent from your IP address has been blocked. 550-5.7.1 Please visit http://www.google.com/mail/help/bulk_mail.html to review 550 5.7.1 our Bulk Email Senders Guidelines. x12si10440172wia.27 - gsmtp (in reply to end of DATA command))
Jul 22 10:00:16 thehostname postfix/cleanup[9609]: 372F91E4483: message-id=<[email protected]>
Jul 22 10:00:16 thehostname postfix/qmgr[3276]: 372F91E4483: from=<>, size=3167, nrcpt=1 (queue active)
Jul 22 10:00:16 thehostname postfix/bounce[9614]: 979BD1E447E: sender non-delivery notification: 372F91E4483
Jul 22 10:00:16 thehostname postfix/qmgr[3276]: 979BD1E447E: removed
Jul 22 10:00:16 thehostname postfix/local[9617]: 372F91E4483: to=<munin@thehostname>, relay=local, delay=0.13, delays=0.05/0.01/0/0.06, dsn=2.0.0, status=sent (delivered to command: procmail -a "$EXTENSION")
Jul 22 10:00:16 thehostname postfix/qmgr[3276]: 372F91E4483: removed

I don't know why the trivial-rewrite doesn't work as expected for the munin user and why doesn't it get a proper sender address before the email is sent on the internet.

Other programs like fail2ban succeed to send emails and are rewrote to [email protected]...

Here is the interesting part of my configuration:

myhostname = realdomain.tld
mydomain = thehostname
mydestination = localhost.localdomain, localhost, $mydomain, $myhostname
myorigin = $myhostname
mynetworks =
relayhost =

I think there must be something I don't understand in the rewrite process!

EDIT

I found this on an article talking about postfix addresses rewriting.

Rewrite user to user@$myorigin

This feature is controlled by the boolean append_at_myorigin parameter (default: yes). The purpose is to get consistent treatment of user on every machine in $myorigin.

I haven't changed the append_at_myorigin parameter, which should be set "yes". $myorigin is set to realdomain.tld, but the rewriting goes wrong and choose $mydomain instead.

postfix

1 Answers

  1. From the first log line

    Jul 22 10:00:15 thehostname postfix/pickup[3167]: 979BD1E447E: uid=110 from=<munin@thehostname>

    we can conclude that munin daemon set sender as munin@thehostname not munin only (without domain part) as your assumption.

    As a proof, I send email via sendmail CLI

    $ mail [email protected]
Subject: test
test

    Above command will add queue in queue_directory/maildrop. Run postcat command to view the queue content

    $ sudo postcat -q 5A1AD347819 
*** ENVELOPE RECORDS maildrop/5A1AD347819 ***
message_arrival_time: Thu Oct  9 23:02:43 2014
named_attribute: rewrite_context=local
sender_fullname: User
sender: myuser
recipient: [email protected]
*** MESSAGE CONTENTS maildrop/5A1AD347819 ***
To: [email protected]
Subject: test

test
*** HEADER EXTRACTED maildrop/5A1AD347819 ***
*** MESSAGE FILE END maildrop/5A1AD347819 ***

    In this case the sender was only myuser without domain part. Here entry of maillog when sending.

    Oct  9 23:05:11 web postfix/pickup[79682]: 9808834784D: uid=1010 from=<zagalo>
Oct  9 23:05:11 web postfix/cleanup[79684]: 9808834784D: message-id=<[email protected]>
Oct  9 23:05:11 web postfix/qmgr[79683]: 9808834784D: from=<[email protected]>, size=318, nrcpt=1 (queue active)

    So, trivial rewrite has nothing to do in your case. Your email has proper sender address, so it hadn't rewritten.

    Solution?

    • Tell munin to change the sender address (my quick googling didn't provide useful results).

    • As alternative, set smtp_generic_maps to providing the rewrite for your munin.

      /etc/postfix/main.cf:
    smtp_generic_maps = hash:/etc/postfix/generic

/etc/postfix/generic:
    munin@thehostname       [email protected]
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