Re: [exim] exim 4 - relay_from_hosts

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Author: Graeme Fowler
Date:  
To: exim-users
Subject: Re: [exim] exim 4 - relay_from_hosts
Robert

Robert Cates wrote:
> I appreciate the help, but my ISP does not block any ports, so I don't think
> I need to do any port forwarding, and I do have -


The other posters aren't talking about port forwarding, they're talking
about the (deprecated but still in use) SSL-on-connect usage of port 465
and the use of port 587 as an MSA (Message Submission Agent) port. Port
25 is historically used for everything - MTA (Message Transfer Agent)
and MSA together, but there's momentum now behind getting users to use
port 587 and authentication in many quarters. It makes applying local
policies to submitted (as opposed to relayed from other MTAs) messages
rather more easy.

>   accept
>     hosts = +relay_from_hosts
>     control = submission/sender_retain

>
>   accept
>     authenticated = *
>     control = submission/sender_retain

>
> but my relay_from_hosts list is empty. Do I need to add the dial-up ISP
> domains/IPs to dc_relay_domains in the update-exim4.conf.conf to allow my
> roamers to send mail through my exim?

Under no circumstances do that! That way madness lies - other users, who
aren't yours, using the same ISP will be able to relay arbitrarily.

Make your users use port 587 for outgoing email, and make them
authenticate. That way you can allow them to do so from anywhere in the
world and you have an easy recipe for tracking any abuse.

Graeme