[Exim] Exim/IMAP/Webmail

I was wondering if this is an exim or an IMAP question. I am using exim
3.12 (debian) with SquirelMail and imap. I tend to get a bunch of these
messages for users..

Date: 30 Oct 2001 14:10:02 -0500
From: Mail System Internal Data <MAILER-DAEMON@domain>
Subject: DON'T DELETE THIS MESSAGE -- FOLDER INTERNAL DATA
X-IMAP: 1004468990 0000000002

This text is part of the internal format of your mail folder, and is
not a real message. It is created automatically by the mail system
software. If deleted, important folder data will be lost, and it will
be re-created with the data reset to initial values.

Any ideas?