[Dovecot] How to specify /var/spool/mail/m/i/mike

[Network Operations]

I was wondering if somebody could tell me how I can tell dovecot (IMAP) 
to read users' mail boxes at /var/spool/mail/{1st char}/{2nd 
char}/username .

For example:
Mailbox for user 'mike' would be located at /var/spool/mail/m/i/mike
'karen' would be at /var/spool/mail/k/a/karen
etc...

Is this possible is version 1.1.6?

Please advise.

Thanks
JB