You can add additional users for your webmail via Icewarp admin panel by following the below simple steps:
1) Login into IceWarp WebAdmin panel with an 'administrator' privilege account via the below URL to manage domains and users.(http://mail.bytehouse.co.uk/admin/)
2) Click the option as shown below:
3. Click 'New User'
Now, you can see the following dialog box
4) Enter the details:
FIRST NAME : First name of the user
LAST NAME : Last name of the user
ALIAS : The email address of the user
5) Click 'save'.
Sample is shown below:
You have succesfully created a new user :)