Thats the problem. The CP does not store users and passwords in MySQL. Its a standard installation with Courier, Courier-IMAP and Postfix. Postfix was installed without any MySQL support too.
I have tried installing PostfixAdmin but was having issues with the creation of mail directories using scripts, so I have basically given up on that route as its taking too much of my time to configure it.
Is there any other way to manage the passwords if it was just a standard installation of Courier, Courier-IMAP and Postfix? Thanks again.