Mention creates a new user if it does not find one

[gb-123-git]

The Addon creates a new user in the DB if it does not find a user. eg
If you mention @T1T2, and T1T2 is not in the DB, a new user with username T1T2 will be created.

This should be avoided as at times the addon has created a duplicate usernames. In case a user is not found, simply it should be ignored and no mail should go.