[CentOS] Do I need large Cyrus DB files?

While investigating my earlier Sendmail confusion I noticed these files:

# ll /var/lib/imap/db/
total 15952
-rw-------  1 cyrus mail    16384 Jan 22 04:02 __db.001
-rw-------  1 cyrus mail   663552 Jan 22 04:02 __db.002
-rw-------  1 cyrus mail    98304 Jan 22 04:02 __db.003
-rw-------  1 cyrus mail 22568960 Jan 22 04:02 __db.004
-rw-------  1 cyrus mail    32768 Jan 22 04:02 __db.005
-rw-------  1 cyrus mail       64 Jan 22 04:02 log.0000000001

The date/time stamps suggest that these files were create by a cron job 
the day after I installed CentOS v4.2 and have not been modified since.

I haven't done any explicit Cyrus configuration, and actually I don't have 
a clear idea of what mail-related functionality Cyrus actually provides.  
If it is in use at all on my system it is done as some aspect of the 
default CentOS4 installation.  Those __db files are not owned by any RPM 
package, although the /var/lib/imap/db/ is owned by the cyrus-imapd 
package.

Do I really need a 22MB empty database file on my system?