Linuxdoc Linux Questions
Click here to ask our community of linux experts!
Custom Search

1. Introduction

Qmail, VMailMgr and Courier-IMAP are a very powerful and easy to use solution, but they are not what I would consider easy to setup. I hope this document helps with that.

1.1. What is Qmail and why should I use it?

Here is the authors (Dan Bernstein) blurb:

Qmail is a secure, reliable, efficient, simple message transfer agent. It is meant as a replacement for the entire sendmail-binmail system on typical Internet-connected UNIX hosts.

It offers POP3, and IMAP (with the help of Courier-IMAP) so that you can use any mail client you prefer.

Secure: Security isn't just a goal, but an absolute requirement. Mail delivery is critical for users; it cannot be turned off, so it must be completely secure. (This is why I started writing qmail: I was sick of the security holes in sendmail and other MTAs.)

Reliable: qmail's straight-paper-path philosophy guarantees that a message, once accepted into the system, will never be lost. qmail also supports maildir, a new, super-reliable user mailbox format. Maildirs, unlike mbox files and mh folders, won't be corrupted if the system crashes during delivery. Even better, not only can a user safely read his mail over NFS, but any number of NFS clients can deliver mail to him at the same time.

Efficient: On a Pentium under BSD/OS, qmail can easily sustain 200000 local messages per day---that's separate messages injected and delivered to mailboxes in a real test! Although remote deliveries are inherently limited by the slowness of DNS and SMTP, qmail overlaps 20 simultaneous deliveries by default, so it zooms quickly through mailing lists. (This is why I finished qmail: I had to get a big mailing list set up.)

Simple: qmail is vastly smaller than any other Internet MTA. Some reasons why: (1) Other MTAs have separate forwarding, aliasing, and mailing list mechanisms. qmail has one simple forwarding mechanism that lets users handle their own mailing lists. (2) Other MTAs offer a spectrum of delivery modes, from fast+unsafe to slow+queued. qmail- send is instantly triggered by new items in the queue, so the qmail system has just one delivery mode: fast+queued. (3) Other MTAs include, in effect, a specialized version of inetd that watches the load average. qmail's design inherently limits the machine load, so qmail-smtpd can safely run from your system's inetd.

Replacement for sendmail: qmail supports host and user masquerading, full host hiding, virtual domains, null clients, list-owner rewriting, relay control, double-bounce recording, arbitrary RFC 822 address lists, cross-host mailing list loop detection, per-recipient checkpointing, downed host backoffs, independent message retry schedules, etc. In short, it's up to speed on modern MTA features. qmail also includes a drop-in ``sendmail'' wrapper so that it will be used transparently by your current UAs.

1.2. What is VMailMgr and why should I use it?

VMailMgr is:

A password checking interface between qmail-popup and qmail-pop3d which replaces the usual checkpassword, as well as an authentication module for Courier IMAP, that provide access to the virtual mailboxes by one of three methods:

  • IP-based virtual server access (invisible to the POP3 user)

  • username-based access (username-virtualuser)

  • hostname-based access (virtualuser@virtual.host or virtualuser:virtual.host)

You should use it if:

You prefer to have the users manage their own domains email accounts, and store their email in their own home dir. (This makes setting up disk space quotas much easier)

1.5. Working configurations

Though this document is only able to cover a snapshot in time on a limited number of setups, I am pretty confident that it can help you get your email system up and running. Combinations that work for me are:

  • RedHat 7.2, Qmail 1.03+patches-18, VMailMgr 0.96.9, Courier-imap 1.4.3

  • RedHat 6.2, Linux 2.2.14, Qmail 1.03+patches-12, VMailMgr 0.96.6, Courier-imap 0.31

  • Mandrake 7.0, Linux 2.2.13, Qmail 1.03+patches-12, VMailMgr 0.96.6, Courier-imap 0.31

  • Debian Potato, Qmail 1.03, VMailMgr 0.96.9, Courier-imap 1.4.3

1.7. New versions

The newest version of this can be found on my homepage http://www.clearrivertech.com/linux/HOWTO as SGML source, as HTML and as TEXT. Other versions may be found in different formats at the LDP homepage http://www.linuxdoc.org/.

1.9. Version History

v0.1 (April 18, 2000)

  • Preview version, wasn't in HOWTO format.

v1.0 (April 18, 2000)

  • Minor corrections.

  • Added details and put into HOWTO format.

v1.1 (April 19, 2000)

  • Minor corrections.

  • Restructured RPM install step.

  • Added source compile and install steps.

v1.2 (April 19, 2000)

  • Minor corrections.

  • Fixed source compile locations and install steps.

  • Added source compile and install steps.

v1.3 (April 19, 2000)

  • Minor corrections.

  • Built proper SGML version (using LinuxDoc DTD).

v1.4 (April 23, 2000)

  • Updated the Courier-IMAP setup information for new VMailMgr version.

  • Switched the license to the GNU FDL.

  • Other minor additions and corrections.

v1.5 (March 11, 2002)

  • Updated the Courier-IMAP setup information for new VMailMgr version.

  • Updated links to various websites.

  • Other minor additions and corrections.

  • Switched SGML from LinuxDOC to DocBook.