The “user ID” or “username” of your email account is the the entire email address in this format: user@yourdomain.com. For example, if the email address you are setting up is john@yourdomain.com, the username must be john@yourdomain.com.
For most email programs, you will only enter in this beginning portion of the address anywhere that it asks for “email user ID” or “email username”.
For full details about managing email in your cPanel and locating settings go to our cPanel Email Instructions.