I have to use the following because I have an extremely large archive of email which was initially created with the uw-imap format:
mail_location = mbox:~/Mail:INBOX=/var/spool/mail/%u:INDEX=%h/.imapidx
The only other change needed is in the authetication section:
turn off "passdb pam" turn on "passdb shadow"
To allow Outlook clients to access Dovecot, you will need to add the following to /etc/dovecot.conf
mail_extra_groups = mail
Source: http://forums.fedoraforum.org/showthread.php?t=39977
<comments>Recommended_changes_to_the_Dovecot_config_to_allow_Evolution_as_a_client</comments>