Re: mail server

Davide wrote:
I need to configure a brand new mail server for a customer who will use
it for mailing and distribution list.

What are the rules (rfc or web documents) to follow to build a strong
mail server without risk to goes into a spamming o black list?

I will use solaris to do this.

Here are some rules that I know of:

(1) Pick an MTA that doesn't have security problems. If there are
security patches, apply them quickly.
(2) Configure the MTA not to be an open relay. This is the single
most important one.
(3) Pick an MTA that follows the RFCs. Luckily, that's really not
too hard; mostly only custom spam software breaks them.
(4) Make sure you have DNS properly set up. There are blacklists
that will add you if your PTR record doesn't point back to your
hostname, etc. This is because there is a positive correlation
between hosts with misconfigured DNS and hosts that send spam.
(5) Do virus checking of some type so that you aren't forwarding
viruses through your mail server. That means checking for
outbound (from your site to the rest of the world) and inbound
viruses, not just one direction.
(6) Don't send any spam! :-)
(7) Don't use a dynamic IP address. There are blacklists for that too.
(8) Don't put up any web forms that can be exploited to send spam
through your server. I'm talking about the "Tell a friend about
this page! Just enter an e-mail address and your message here!"
type. These can be used to cause your server to send spam, so
that boils down to #6.

You probably also want to filter spam that arrives at your mail
server. For that, SpamAssassin works well, but you can also use
a few other techniques like sendmail's greet-pause feature (or
a similar feature in another MTA) or greylisting.

- Logan
.

Relevant Pages

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  • Extended 5xx code (was Re: Drop UCE instead of forwarding off-site?)
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