no access to cyrus imap server

[Christian Christmann <plfriko@yahoo.de>]

Hi,

I've just installed the Debian cyrus imap server packages
on my mail server. Unfortunately, I can't connect to the imap
server with my email clients which are running on my client
boxes. When I install sylheed-claws on the server I can access
the IMAP directories without any problems.
Of course, I can ping the mailserver and also nmap tells me that
port 143 is open. Futher, I can connect to the server with my client
boxes using "telnet 192.168.1.1 143".

Any ideas how to solve the problem?

Thank you

Chris