Hi,
I'd like to know what kinds of mail servers people are running on *nix boxes. I have had an old mail server running Exim delivery to local mbox format in user's home folders and imapd for client connections.

My new server (which a nice young lady set up for me) is running Postfix with a DBmail backend on MySQL, using dbmail to supply the imap daemon for the clients and putting it through dspam and clamav, which annoyingly changes the subjects of the emails with [SPAM] (especially annoying if they're not spam and then you're stuck with marked emails) but anyway, I may change this later...

I am a little concerned that this setup may blow up some time in the not too far future. I've already seen an alert from my monitoring server that MySQL has too many connections. I can increase this no doubt, but I just don't have all that much faith in the scalability and reliability of this server like I do with say Exchange which I had in my previous workplace.

It already consumes over twice the storage space of the old server (Exim/mbox) and I have had one or two minor issues with it already. It feels like there are too many things that can go wrong with it and if any of them break then the whole thing breaks.

I am very interested in other people's experiences with mail servers so I have something to compare to. Could you please share your experiences; which mail servers you have run in what configs with what users?

thanks

Well..none I have run, as part of a testing scheme in the mil, umm if I recall right it was Postfix and Dovecot, also tried Sendmail out of interest..postfix and dovecot were easy ones, but since it wasn't my main point I didn't build the thing completely, just in a lab environment of my own.

We run Exim and mbox, with probably about 2,000 active accounts. Here in the UK Exim seems to be the MTA of choice for large organizations (universities, ISPs, etc.), but my personal mail provider has used Postfix for their system since the start with no issues that I'm aware of, and they have a very large base of subscribers.

I haven't used it personally, but I beleive that Carnegie Mellon's Cyrus has been a very popular choice for providing mail store and IMAP facilities on larger networks for a while now. Red Hat and Apple include it in their current server products.

To be fair to DBmail though, any database-backed mail service will be much more complex and resource-hungry than Exim+mbox, and will be heavily dependant on the database. I've resisted moving to Exchange partly because of my concerns about the Exchange database.

My instinct is your problems are a) a MySQL issue (which just may be that it needs more RAM to service all the requests), and b) that you personally aren't comfortable with working with the guts of this system, and would prefer the complexities either hidden away (as Exchange does) or handled by someone else. If it helps any, I've come to feel that a full email facility is probably the most complex arrangement of technology on any network, and that many organizations probably ought to consider using a separate admin or outside provider rather than asking the regular admins to navigate the tangle of services and technologies involved in maintaining a mail facility.

I have setup a mailserver with postfix as smtp, dbmail as imap, imapproxy as imap proxy, amavisd-new as spam and virus scanner front-end , clamav as the antivirus and spamassassin as the spam scanner, and not forgotten squirrelmail as the web front-end. So far no problem at all. that's because I have a powerful machine (2 Xeon procs, 32 GB SCSI, 1 GB RAM, 64 bit, 64-bit Linux). MySQL is the database of choice for dbmail. Use Innodb type rather myISAM. I really like dbmail. Storing emails in database is a Good Thing(tm)! lol . I recommend this setup to everyone.

I heard cyrus is very good too. It uses its own database format but the concept is the same. Storing emails in database. Bear in mind that dbmail is a new program compared to cyrus but so far it is stable and very fast.

SMTP - Qmail (smpt-auth)
imaps - couirer-imap (SSL)(auth)
pop3 - courier-pop3 (SSL)(auth)
webmail - squirrelmail (HTTPS) (poppassd plugin)
virus - clamav (qmail_scanner)
spam - spamassassin (qmail_scanner)

That's my setup.

a flood of help, thanks!

I am interested in checking out this squirrelmail and improving my knowledge of Posfix and Exim since they seem to be well regarded MTAs. Gotta check out that old classic sendmail as well...

from what i've read, sendmail sounds like something made by microsoft in terms of security issues. qmail on the other hand has no such problems.

Mandriva: Updated sendmail packages fix DoS vulnerabilities
30th, August, 2006

http://www.linuxsecurity.com/content/view/124767

Debian: New sendmail packages fix denial of service
24th, August, 2006

Updated package.

http://www.linuxsecurity.com/content/view/124677

these are just from the 2 newsletters i've kept in my mailbox, but i'll bet there are more.

SMTP - qmail-send (smpt after POP SSL)
imaps - couirer-imap (SSL)(auth)
pop3 - qmail-pop3d (SSL)(auth)
webmail - squirrelmail (HTTPS)
virus - clamav (qmail_scanner)
spam - spamassassin (qmail_scanner)

That's my setup.

you may also try:
http://www.qmailtoaster.com/

My setup:

smtp - postfix
imap - cyrus-imap
webmail - squirrelmail (https)
spam - spamassassin
authentication - mysql

Using a database to store your mail will slow you down. It is more neat and will allow you to organize your mailbox in a much better way but doing mega lookups on a SQL database takes more resources, especially the bigger it gets. It may also be that you need to setup your indexes.

What I like about cyrus-imap is that it is very fast and easy to administer once you learn it well. It also includes easy setup of virtual domains, access control lists for mailboxes, domain quota and user quota, individual domain administrators, filtering (vacation autoreplies, forwarding, spam, custom), shared mailboxes, public mailboxes. It is also very fast because it uses header indexes. The messages are stored as text files but it is the indexed files that do all the lookup work. It is trully the best mailbox server I have worked with. However, the learning curve is a bit more slanted.

I don't know cyrus because I don't use and have one. I just think that the idea of storing emails into database is a very good idea. Storing, retrieving and backup (in case u need to migrate from one machine to another or from one OS and another) is easy. You just need to backup and restore the data and I don't see it slow compared to file-based setup like maildir or mbox format. FYI, dbmail is new and many room for improvement.

SMTP - Exim
imaps - custom
pop3 - custom
webmail - squirrelmail (HTTPS)
virus - clamav
spam - spamassassin

I use the default Sendmail on all my OpenBSD systems that do not need to accept inbound mail.

Postfix for all my machines that actually accept and store (or relay) mail (because it's much easier than Sendmail to configure).

dovecot for providing IMAP/POP access to mailboxes (again, very easy to configure).

The company I work for also uses Postfix embedded into our e-mail filtering products and we find it to be very stable and fairly fast. We're using a MySQL database for a lot of the settings and lookup tables, but we don't actually store mail in the DB.

It sounds like the misgivings you're having with your setup are due the the overall complexity. MS Exchange is actually vastly more complex, but most of that is hidden. For instance Exchange uses a JET database, but most admins don't know that because they rarely have to deal with it. The problem with cobbling-together Open Source tools is that they're... well, cobbled-together. You have lots of options for the MTA, lots of options for the DB, lots of options for the MDA, etc, etc... You can build a solution by picking 5 different pieces of software, but they're all distinct and managing their operation is difficult if you ever need to upgade one piece and that causes incompatibilities with another piece.

Personally, I would recommend a full package groupware product for use in a corporate environment. Something like Zimbra, Openexchange, etc...

I'm running sendmail (mostly because I've been in the Sendmail world long enough that I can configure it to do most of what I need), and cyrus because some of my sites have either lots of users or large mailboxes or many virtual domains, and cyrus can handle all of the above scenarios.

I will assert that getting multiple proprietary software packages to play nice can be as bad as open source packages. If setting up multiple bits to assemble the system is not desirable, one can purchase a support contract and have someone else deal with the system integration - and support may be a good idea with the large packages as well.

And of course, I use multiple open source email servers - postfix and cyrus being two of the largest ones.