There are cases where administrators don't want to allow users to have blank emails, yet they want to have special user accounts with no email account to avoid building up queues or causing email failures. Examples of this are:

• anonymous user account.
• The "community" user that I added to this tracker and similar users that represent a non-registered user or some queue of work.
• user account used for incoming emails that don't map to a registered user

The code that consumes the email address handles blank emails, so we just need to disable the blocking of blank emails when logged in user is an administrator.