WARNING: This program works (for me), but part of its operation is
deleting files from disk. DELETING FILES FROM DISK! Don't use it unless
you know what you're doing.

Moirai
------

With this program you can set a "shelf life" for files: When a file
hasn't been modified (mtime) for a specified time, it is deleted.

Klotho and Pieria
-----------------

With these two programs you can set the shelf lives of emails in a
maildir through Mutt. Actually their principle of working can be
generalised to work around a serious (to me) problem in Mutt: you
cannot execute an external command on the currently selected email.

One could also use Mutt-Guile to do that, but I am not sure of that
project's status. And after all: Who uses Mutt anymore?

Themis
------

This little scripts extracts the Date: fields from emails and adjusts
the mtimes accordingly. Maildir only, of course.

Note
----

This is just a quick hack. I hope to have the time to make a proper
package of this, but that may as well be never. However, if you send me
and email and kindly ask for a package, I might create one in
relatively short time.