[exim] Possible setup EXIM to use mbox

Dear Sirs,
I have exim-4.80.1 installed at my FreeBSD-8.0 (amd64) server. In order to use
my webmail program, I need to setup exim-4.80.1 to use mbox instead of maildir
that as I understood is the default value.
My question is: Can I setup exim-4.80.1 to use mbox? If yes, can you guide me
how to make the necessary changes in the config file(s).

Please try to help me, it is very important to me!

Many Thanks & Best Regards
Mike Kranidis