I have followed the instructions in "The Book Of Postfix" and have a working installation of Postfix and Courier-imap. Authentication is against /etc/passwd.

Today I added in support for another domain I am hosting. I've added the appropriate info into /etc/postfix/main.cf and created a virtual domain mailbox, alias & recipient maps are handled via hash files. Postfix can successfully receive mail for the virtual address I have setup and I can read the mail in /var/spool/virtual_mailboxes/<mailbox>.

The problem now is accessing this mailbox via IMAP. My Linux-fu is still weak and I don't know how the virtual domain mailboxes are accessed and how authentication is performed

Any help much Appreciated.