I would like to find a way of avoiding the m###### type of email login. So I'm hoping to get either confirmation or correction of the way email addys and user names interact. This is my understanding of how it works, based on creating test users and addresses.
1) If you create an email address using the Mail > Manage Addresses > Create New Address interface, then the login for that address will be in m####### type.
2) If you create an email address at the end of the Add New User process, then the login for that address will be the same as the username.
3) If you do NOT use option 2 (above), then there is no way to later create an email address that uses the username for the login.
4) If you DO use option 2, after having first used option 1, then if the new user name has the same name as the previously created email name, that name is no longer available as an email address for the new user, AND there is no way of associating the two in the system so that the m###### login can be discarded.