Re: Exim and SMTP on an internet gateway
Tim Sailer wrote:
Now, we have a split-dns setup, so the hosts/IPs seen outside our
firewall don't actually point to the real machines in most cases,
and the SMTP gateway uses our internal DNS, so knows how to deliver
mail properly. Without split DNS, you can do this with creative use
of /etc/hosts (I think) but DNS/MX would do the job for you.
WARNING! If you go that way without further bastioning, you will create
an open relay - and thus be blackholed faster than you could imagine.
Make sure, that mail ONLY is accepted if it (exclusively) either
1.) comes from LAN and goes out
2.) comes from outside and goes to LAN
Usually MTAs look at MX records for mail delivery, so you won't be able
to use /etc/hosts for fudging - that file only can do A/PTR entries
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