E-Mail Server Setup Advice?

dhammala asks: "I am responsible for setting up and maintaining a mail server for small web-hosting type business. We currently host about 75 domains, around 100 mailboxes and due to the efforts of our sales team, we are wanting to get ready for some great increases in those numbers. I am worried about my current configuration and ease of administration. More importantly (well, at least to the customers) is email deliverability -- it seems that messages delivered to some big players are being marked as SPAM or disappearing altogether. I am asking the Slashdot community for it's insight and advise on 1) if my current choice of software/configuration is a good match for this situation and 2) if there any additional measures I might take to ensure email deliverability?" "Here is an overview of our current setup:

• We lease servers at ev1servers.net.
• The servers are running RHEL ES3.
• We chose to use Postfix and have it configured to support virtual users and domains mapped in MySQL tables. The reference I used to configure this setup is located here. We initially chose Postfix over qmail because it was open and over sendmail because the config files are actually readable.
• I have added in SQLGrey grey-listing for Postfix to provide a simple level of SPAM detection for our users. We are not wanting to deal with the customer service and higher box loads of mail scanning at this time. We might choose to use a 3rd party vendor to do this as needed.
• Messages are delivered locally via maildrop in maildir format.
• Courier IMAP is running to support both IMAP and POP access to the mailboxes.
• Postfix Admin was setup for easy mailbox administration.

For deliverabilty, I have/am taking the following steps:

• I have verified that our reverse IP records are correct
• I have created SPF records for all of the domains
• I have verified that our server is not listed in any blacklists (great scanner at dnsstuff.com)
• I have started to install DomainKeys for Postfix

In doing all of that, I have found that our IP is listed in the BlarsBL. Do I need to be concerned about this rogue list? The IP was there before I even began to setup the box.

I have not yet been able to get DomainKeys to work with Postfix. It was during my configuration attempts that I started to question this setup and wondered if this was the best setup for our situation.. this inquiry has lead to this posting.

In a perfect world, I would have an email server that:

• is easy to administer,
• supports automated mailbox setup/removal (currently I can just insert rows into my tables and the mailbox setup is done)
• supports current technologies, like grey-listing, DomainKeys, etc
• is secure
• makes the best use of system resources -- I want to get the 'best bang for the buck'

So what do you think? If I stick with this setup will life be grand? I am open to something new AND even taking the time to learn a new setup. If I do need to switch to something different, my only concern would be the ability to migrate existing mailboxes and messages over to the new setup.

Are there any other technologies or configurations that I need to implement to support the best deliverabilty rates?"

Comments

Personally...

[Shads]

... after hosting using Exim3 and Exim4, Postfix, and Sendmail... if i were doing a "Large" config again (read 1000+ domains, 30k+ accounts) I wouldn't consider anything *but* sendmail. It's not the easiest, newest, or anything like that, but it does scale extremely well. The setup I'm currently using (about 10 domains, 70ish accounts) is:

Exim4 SMTP
Dovecott IMAP and POP3
Bogofilter
Spamassassin (SA-Exim)
Clam-AV

It's a rocking system, I'm currently having about 18000 messages a day tossed at me of which about ~17000 are spam. My personal accounts were getting about 2500 spam/day until I enabled all the anti-spam software and virus removal. I now get about 1-2 Spam a day and I've not had a single false positive.

For a small mid range setup I would probally use exim4. It's simple, has great features, and it's nice to have spamassassin at smtp time instead of having to process the entire message.

I don't recommend standard RBL's, however, the URI RBL's are *extremely* effective and an order of magnatude more sane in what they block (eg: if the message contains a link to viagraforyou.com it blocks the message, rather than blocking random dsl servers and /16 netblocks of ip addresses to catch a single spammer... some of the standard rbl's are nutzo.)

Theres a nice tutorial and informational link about using all the good features of sendmail and several additional ideas and theories on what is effective and what isn't at http://acme.com/mail_filtering/ the guy gets *insane* quantities of mail (mostly spam) and tells how he deals with it.

Synopsis: Large site- Sendmail, Medium/Small Site- Exim4.

Alot of people like qmail and postfix over sendmail and exim, but I just don't care for them having used them. Although if forced to choose between postfix and qmail it would be qmail.