Running own mail server

[Jim Garrison]

>
> Hi
>
> I'm in the middle of a similar exercise - I found the DNS how-to
> extremely helpful. You might want to give it a shot. I bought the
> o'reilly books too, but the how-to really does cover stuff very
> quickly. I had always thought dns was a minefield, but once you look
> at it logically for your network it all makes sense fairly quickly. I
> guess I'm a month into it now from my first stab at it. It's well
> worth the effort I do have to say.
>
> Best of luck
>
> Bry

I think you'll find that trying to run OUTGOING mail from your server
will be a
continuous exercise in frustration.  The IP address you get will be in a
netblock of
known DSL addresses, and will probably have an rDNS entry that also
identifies
it as a DSL line.  Many spam blacklists (RBLs) automatically block DSL
netblocks
and rDNS entries because of the simple fact that a huge percentage of spam
originates at these addresses.    Here's what happens if your SMTP server is
configured to deliver mail directly:

1) You send an email from a client on your internal network
2) It goes to your SMTP server
3) Your SMTP server determines where to send the email and connects to
   the destination SMTP server.
4) The receiving server looks up your IP address in one or more blacklists.
   Your netblock appears on these blacklists, so a positive response is
returned.
5) The receiving server rejects (bounces) the mail

While you will  be able to RECEIVE email just fine (after you get the
DNS set up
correctly), you will probably have to continue using your ISP's SMTP
server for
outgoing mail.   You can accomplish this one of two ways:

1) Configure each internal email client to use the ISP SMTP server directly
2) Configure the internal email clients to use your SMTP server, and then
   configure your SMTP server to forward all mail through your ISP's server
   (called "smarthost").

Also, consider that properly configuring an email server is a non-trivial
exercise, and improper configuration can lead to an open relay (where
anybody
can send mail through your server), which will get your address on
blacklists
(if it's not there already).  Not only that, many blacklists are
voracious and
spiteful, and will blacklist an entire netblock based on a single open relay
violation.  Not only will your address be blacklisted, but everybody
else in
the same netblock.

Poorly configured open relays are a major source of SPAM.  Please do not
attempt this until after you have learned MUCH more about SMTP and DNS.