postmail - local mail filtering

Hi guys,

I'm hoping someone here can point me in the right direction.
I'm using the latest postfix with saslauthd using pam, which works
great.
The problem is I need to configure postfix to deliver mail to
/var/spool/mail/ in alphabetical order.

Example:

Auser would have the local mail delivered to /var/spool/mail/a/auser
Buser would have the local mail delivered to /var/spool/mail/b/buser
Cuser would have the local mail delivered to /var/spool/mail/c/cuser


So basially I need to be able to configure postfix to filter the local
mail and place it in the right directory.

Also what do you guys use for a pop3 server and what to you recommend.
Previously I was using sendmail with procmail and cucipop.

I love using cucipop but I was thinking of using qpopper although the
on-line documentation is somewhat limited.

TIA, P