Not so long ago I have found that exim is sending mail4root emails and logs them into /var/mail/mail. Example from exim log:

2016-07-19 09:39:02 1bPOgI-000370-1Q <= root@example.net U=root P=local S=78459 2016-07-19 09:39:02 1bPOgI-000370-1Q => /var/mail/mail <root@example.net> R=mail4root T=address_file 2016-07-19 09:39:02 1bPOgI-000370-1Q Completed 2016-07-19 09:40:18 Start queue run: pid=12117 2016-07-19 09:40:18 End queue run: pid=12117 2016-07-19 10:09:02 1bPP9K-00042T-LK <= root@example.net U=root P=local S=78459 2016-07-19 10:09:02 1bPP9K-00042T-LK => /var/mail/mail <root@example.net> R=mail4root T=address_file 2016-07-19 10:09:02 1bPP9K-00042T-LK Completed 2016-07-19 10:10:18 Start queue run: pid=15678 2016-07-19 10:10:18 End queue run: pid=15678

Can someone explain what causes it?

  • R=mail4root indicates that you have a router of that name in your config. Presumably, its purpose is to pass messages addressed to root to the address_file transport, which in turn delivers them to /var/mail/mail. Are you using the default exim config for your OS?
    – D_Bye
    Jul 19, 2016 at 14:31
  • @D_Bye Yes, default installations. I found out what was the problem, php-snmp was not configured. I just did apt-get install snmp. Turned out these emails was not the cause, but the symptom. Looks like somewhere in the system there is a problem with dependencies and some task calls php-snmp periodically.
    – Samurai_w
    Jul 19, 2016 at 14:58

1 Answer 1


As a security measure Exim will not deliver email to root. The mail4root router is a last ditch handler to deliver mail for root to the mailbox for mail.

Normally, an alias for root would be configured in /etc/aliases to deliver to the system administrator's personal mailbox. There are a number of aliases that redirect to root as they should be handled by the system administrator (root). They also get redirected if the alias exists.

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