outlook as a client

[Tom McLoughlin]

I have several accounts whose mailboxes on a cyrus-imap server are 
connected by Outlook. However, they are able to download mail from the 
server, but they cannot create emails from the outlook client on a 
remote machine and be read and connected to the cyrus-imap server for 
processing. A friend says he has tested sendmail and the cyrus 
installation and all seems correct.

How should I proceed?

Thanks