Re: [EXIM] Sender verification

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Author: Philip Hazel
Date:  
To: Wouter Meuleman
CC: exim-users
Subject: Re: [EXIM] Sender verification
On Wed, 7 Jul 1999, Wouter Meuleman wrote:

> Would it be able to somehow filter every mailmessage that a users

sends, check the UID or GID of that user and deliver it accordingly? So
that if a user that isn't allowed to send internet-mail will get an
error-msg stating this when he/she tries to.

If you add something like

condition = "${if eq {${domain:$sender_address}}{your.domain}\
{${lookup{${local_part:$sender_address}} lsearch {/some/file}{$value}{0}}}{1}}"

to your lookuphost router, then bingo!, all local users who are not in the
file are denied, and all those who are in the file may or may not be
denied, depending on the contents of the file. Of course you can make
the default the other way. I have not tested the above. It may be buggy.

The disadvantage of this is that the error message will be "unknown mail
domain". I guess you could add a subsequent domainlist router, with the
same test, but inverted (so it acts only for your denied users) to route
failing messages to an autoreply transport instead, and use this to send
an explanatory reply.

Naturally this doesn't stop your users from sending external mail by
direct telnetting, if you permit Telnet.



-- 
Philip Hazel            University of Cambridge Computing Service,
ph10@???      Cambridge, England. Phone: +44 1223 334714.



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