Postfix and Apple IMAP

I am setting up a new Xserve with OS X Server 10.2.6. I have followed (I think) the instructions given in the Article about installing Postfix in OS X Server. The only difference is that I installed Postfix with Fink. When I telnet into 127.0.0.1 25 here’s what I get

bash-2.05a$ telnet 127.0.0.1 25
Trying 127.0.0.1…
Connected to localhost.
Escape character is ‘^]’.
220 xserve.mcgillis.org ESMTP Postfix

I have a user with a short name of admin who has entry in the local Netinfo database with a basic password. I can certainly log in and out of the Server with this name and password. If I look in /var/mail there is a directory for admin. The problem when I try to contact the IMAP service from an e-mail account in Apple’s mail app, it always returns IMAP server has rejected the password for user admin. Where have I gone wrong?

Thanks