[TriLUG] mail relaying

[Jon Carnes]

There are several ways of doing what you want...
  - Setup the firewall rules so that the external interface rejects anything
on port 25 unless it comes from an internal or local address
  - Setup Sendmail so that it only listens on the local network card (look
in the sendmail.cf files for these rules - or use the M4 file to set it up).
  - Setup Sendmail on an internal server.

You will need to set-up your sendmail server so that it will relay traffic
for the old sites (like Mindspring).  To do this, edit the file
/etc/mail/relay-domains and add the domains that you will relay for.

Have fun - Jon
----- Original Message -----
From: <gregbrown at mindspring.com>
To: <trilug at trilug.org>
Sent: Monday, February 11, 2002 9:31 AM
Subject: [TriLUG] mail relaying


> At last count between myself and my wife we download mail from roughly
seven pop accounts.  Since connecting to Roadrunner I can no longer send all
my mail, regardless of the return address, through my old mindspring SMTP
outgoing mail server and Roadrunner won't forward mail from e-mail addresses
other than xx.rr.com.
>
> From everything I've read setting up a firewall to forward mail is A Very
Bad Thing mostly because of fears of people using your SMTP mail server for
mail spamming.
>
> I am running Red Hat 7.1 on my current firewall.  I have two ethernet
cards: eth0 and eth1.  Is there a way to set up my server to forward mail
that arrives only on eth1 (inside link) while blocking all forwarding
requests coming from eth0?
>
> I've read some of the man pages and looked through my "Linux Bible" book
but I can't find any instructions on how to set this up - just information
on why I shouldn't do this.
>
> Any thoughts, pointers, or suggestions?
>
> Any help would be greatly appreciated.
>
> Thanks!
>
> Greg
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