[Evolution] Sent file too large

[Marcos Pinto <markybob gmail com>]

Evolution is giving me this error:
Failed to appened local `Sent' folder: cannot append message to mbox
file: /home/markybob/.evolution/mail/local/Sent: File too large
What can I do about this, short of deleting my emails or moving them? 
I need to be able to easily search through my emails as I currently
do.  Is there a way to make evolution with Mail-dir format for Sent,
like it does for my Inbox?  If so, how, and will it convert my Sent
mails?  Any other suggestions?
The file is 2G and the filesystem can indeed handle 2G+ files.  I'm
running kernel 2.6.13 on Debian sid with reiserfs.
Thanks,
Marcos