Disabling IMAP authentication
WebMail Pro stores users credentials in the database. But when user logs in, WebMail Pro checks their credentials on IMAP server anyway. The useful side-effect of that behavior is, if account password was changed on mailserver, you just log into WebMail Pro with new password specified, no need to change it anywhere in the settings.
In some cases, it might be necessary to have IMAP authentication disabled. In terms of WebMail Pro it means disabling webmail section, so in AdminPanel you'll need to uncheck Enable webmail box in domain properties. Of course, you will still have other screens such as contacts etc. available to you. It also makes possible to add your own WebMail Pro modules, with no need to have authentication over email.
Once webmail section is disabled, users credentials will only be checked against those stored in the database, so even though email address is used as long, the password doesn't have to match one of the email account itself.
Also, keep in mind that disabling webmail section effectively disables the feature of creating new account on first login, only users with their account set up in WebMail Pro will be able to log in. You can add users with AdminPanel or via Users API of WebMail Pro.