tidy up/remove imap/db/log.* files?

[Carl Brewer]

G'day,
I have a NetBSD box with a very full /var/imap/db directory.  It's full 
of these :
-rw-------   1 cyrus  mail  10485760 Sep  3 08:45 log.0000000779


file log.0000000779
log.0000000779: Berkeley DB (Log, version 16, native byte-order)

There's 534 of them.  Roughly one a day.

What's the recommended way to tidy them up and/or get rid of them?
Cyrus imapd 2.4.17 (from NetBSD pkgsrc)

Thanks!

Carl