[Exim] Dummy POP3 server

Hi all,

sorry for this slightly offtopic post.
Does anyone know of a dummy POP3 server, i.e. a server that accepts any user
and password and reports no mails?

I want to move to an Courier IMAP in the near future and while converting
the mbox files to maildir, no accesses must be made to these files.
Simply shutting down the POP3 server will result in a lot of complaints from
my customers ;-)

Jens