Re: [Exim] Preventing mail deliveries

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Autor: Jeffrey Goldberg
Fecha:  
A: Gary van Blerk
Cc: exim-users
Asunto: Re: [Exim] Preventing mail deliveries
On Thu, 8 Jun 2000, Gary van Blerk wrote:

> I have Exim running on a slackware 7.0 server. I have 120 users that
> require local mail only. Of the 120 users, only 20 require the ability
> to receive and send internet mail.


> How can I restrict the other 100 users from being able to send mail
> out


If I understand correctly the mail is being generated locally (on the host
running exim), if so you can put a condition in your routers which
does a lookup on $sender_ident, something like


lookuphost:
driver lookuphost
transport = remote_smtp
condition = "${lookup{$sender_ident}lsearch{/path/allowed-users}"

(But I almost certainly have the details for the condition wrong.

> and how do I make them unable to receive mail from other domains?


That's easy. Have two localuser directors. The first one has a condition
requiring that the users be in the allowed-users, the second one should
have a "domains" restriction.

> Users are checking their email addresses and sending email to that
> address from home etc.


Ooops, that makes the first one harder. Two options come immediately to
mind:

 (1) make the condition on the From addresses themselves.  This is
     vulnerable to forgery.


(2) Use SMTP authentication and make the restriction based on that.

This was off the top of my head speculation. I've never tried to do
anything similar, so I'm sure others can recommend some thing better.

-j


--
Jeffrey Goldberg
Until July 9: Cranfield Computer Centre
See http://www.goldmark.org/jeff/contact.html for change of address info
Relativism is the triumph of authority over truth, convention over justice.