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phunehehe
Asked: 2013-11-09 20:09:08 +0800 CST

How to make Postfix apply content filter after expanding aliases?

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On my mail server I have an alias from root to my email address (which is handled by the same server). I also have a content_filter that uses ${recipient}. Incoming and outgoing emails work as intended. They get filtered by the content filter with the correct recipient address.

However, when an email is sent to root from the local machine, the content filter is passed [email protected] instead of my email address. After processing the email, the filter hands it back to Postfix, then the local delivery forwards it to the right address.

How can I get the alias to be expanded before the content filter is applied?

Current setup

Here is how I currently have the content filter set up (find more details in INSTALL.md):

  • In /etc/postfix/master.cf:

    gpg-mailgate    unix    -   n   n   -   -   pipe
    flags= user=nobody argv=/usr/local/bin/gpg-mailgate.py ${recipient}
127.0.0.1:10028 inet    n   -   n   -   10  smtpd
    -o content_filter=
    -o more_options=omitted

  • In /etc/postfix/main.cf:

    content_filter = gpg-mailgate
alias_maps = hash:/etc/aliases
local_recipient_maps = $alias_maps $virtual_mailbox_maps proxy:unix:passwd.byname

Other interesting bits

In /etc/aliases:

root: [email protected]

According to the log, the alias is only expanded in the local delivery agent:

Nov 12 10:45:22 server2 postfix/local[29745]: 0AA16792: to=<[email protected]>, relay=local, delay=0.1, delays=0.05/0.01/0/0.04, dsn=2.0.0, status=sent (forwarded as 19F20A53)
email

1 Answers

  1. Best Answer

    /etc/aliases declares local aliases and thus is only used by the local delivery. According to ADDRESS_REWRITING_README, only virtual aliases are expanded when mail is received, not local aliases. The solution is to declare virtual aliases. The local aliases can then be removed.

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