dovecot help

[Darren Grant]

I've just installed and configured a mail server running sendmail + 
dovecot + squirrelmail.

I've configure dovecot to use maildirs:
default_mail_env = maildir:%h/Maildir

I can attach via an email client to the IMAP server... make new folders, 
import mail... but I'm not receiving new emails... instead they're being 
stored in /var/spool/mail/%u.  I can also navigate the users home 
directories and look in their Maildir.

Can anyone please tell me what I have to add to my sendmail.mc or 
dovecot.conf file so that dovecot receives all incoming mail?