mailprocessing

The following programs are part of the mailprocessing package: maildirproc is a program that processes one or several existing mail boxes in the maildir format. It is primarily focused on mail sorting — i.e., moving, copying, forwarding and deleting mail according to a set of rules. It can be seen as an alternative to procmail, but instead of being a delivery agent (which wants to be part of the delivery chain), maildirproc only processes already delivered mail. And that's a feature, not a bug.

imapproc is a program that processes one or more folders on an IMAP server. Much like maildirproc it sorts, e.g. moves, copies and forwards email. It uses the same filter configuration mechanism as maildirproc: a Python script that hooks into maildirprocs processing code.

maildirproc was written by Joel Rosdahl <joel@rosdahl.net> and is distributed under the terms of the GNU General Public Licence.

imapproc was written by Johannes Grassler <johannes@btw23.de> and is distributed under the terms of the GNU General Public Licence, just like maildirproc.

Benefits

So, what's good about using maildirproc instead of a more conventional setup, with a delivery agent like procmail? For me (the author) it's this:

• It's small. maildirproc and imapproc are just small Python programs that are easy to understand.
• It's robust. If there's a syntax error in the configuration, or a bug that makes the program crash, then nothing happens; the mail will not disappear. And as a consequence of using maildirs, no locks are needed.
• The configuration language is relatively easy to understand and use, yet very powerful. The rules are expressed in a full-blown computer language (Python).
• It's easy to test new configuration. Since maildirproc is not part of the delivery chain, it's just a matter of taking down or disabling the process, modifying the configuration and running maildirproc in test mode. When the new configuration is ready, just start or enable the process again.

Download

• For Python 3.x

Source code repository

• https://github.com/mailprocessing/mailprocessing (public Git repository)

Background

For a long time, I used procmail to sort my mail, but I was not entirely happy with its configuration language. I subscribe to a lot of mailing lists and I use several e-mail addresses, so the .procmailrc file was quite large and complex and I found it hard to express mail sorting rules elegantly. I wanted to be able to define and use functions, data structures, if statements, loops and other imperative language constructs and felt that procmail's rule-based vocabulary was limiting. I thought about writing a program to generate the configuration from some higher-level rules, but I never got to it. I also didn't feel comfortable with e-mail sorting being part of the delivery chain. (Granted, procmail can be used in other setups too.)

Then one day I stumbled upon a program called Maildird, written by Jörgen Cederlöf, and I liked its basic design:

Since Maildird was not configurable (at least not at the time) in the way I wanted, I decided to write my own program that worked somewhat similarly but with a configuration style that suited me. If you like it, you are welcome to use (or improve) it too.

Documentation

See the mailprocessing reference.

Examples

See the examples directory.

Installation

mailprocessing has no other dependencies than a working Python on a Unixish system. No special installation is needed: a simple pip install mailprocessing is sufficient . You can also run run python setup.py install.

You can run maildirproc or imapproc in several diffent ways, e.g.:

• Manually: You could, for example, run

  maildirproc --once -r foo.rc -b . -m Maildir

  to apply the program in foo.rc once on a maildir directory called Maildir in the current directory.

• By cron: Put a row like

  * * * * * maildirproc --once

  in your crontab to run maildirproc each minute (using the default RC file ~/.maildirproc/default.rc).

• As a long-running process: Just start maildirproc (without the --once flag).
• Using some service supervision framework, for example runit.