It's possible to have multiple e-mail addresses linked to a single account. Service Desk should allow for settings.

Currently when configuring email requests it allows for e-mail and username:

• As long as the e-mail has not already been used by another project, there will be no errors

Once you get to the next screen where you choose the "Request Type", there is a second check:

• This occurs when the username to access the mail server has already been used by another project.

Alternatively,

• There should be a better message during the mail config if Service Desk will not accept the username.