fetchmail from ISP (POP) to IMAP server

Hi to all, Here is what i pretend to do I have a small LAN with several workstations and a mail server. What i pretend to do is, get mail from ISP pop accounts and place it on /var/mail//. Then mail clients should access their mail throw IMAP. I can't configure procmail in order to place the incomming mail in the user directory /var/mail//. This directory should be the IMAP directory for each user. Does anyone know if i am doing this configuration well? How do i configure procmail to do this? Thanks to all in advance