

Configure debian mail server to reject unencrypted messages? - plg

If I wanted to configure a debian mail server to bounce any messages that are not encrypted with my PGP public key ... is this possible &#x2F; feasible?
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pdx
I would not do this at the server level, but instead, at the user level.

I use postfix as my mail server, and tell it to use procmail for incoming
emails.

Install procmail, and set up a .procmailrc file in your user account. Procmail
is powerful, and let's you run scripts against incoming email, and it also
let's you bounce emails. Combining a script that attempts to decode the email,
with a bounce instruction, if that decryption fails, should get you what you
need.

~~~
mike-cardwell
That is called backscatter and is highly likely to get your mailserver
blacklisted.

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mike-cardwell
With Exim, you could just shove something like this in your DATA acl:

    
    
      deny condition = ${if !match{$message_body}{-----BEGIN PGP MESSAGE-----}}
           message   = We only accept encrypted mail here
    

However, the problem here is that the plaintext has already been sent over the
wire before the message is rejected.

