Gmail says the username is 'already in use' and 'not in use' at the same time
30293
How a Gmail username can be taken but not recognised simultaneously?
144982
Certain usernames not displaying at all
59172
How do I change my default account with Google multiple sign-in?
99513
postfix - how to prevent users from sending with another users name
45300
How to prevent duplicate usernames when people register?
46198
Two separate Gmail accounts
104933
Why are there a lot of users with Reinstate Monica in the username?
70083
Why does Gmail hide email options under a '+' sign?
126983
email field or username for logging in an application?
153070
INACTIVE_OWNER_OR_USER
57385
When adding another Google login, user should get routed to Google Multi-Login screen
142050
Why does Ubuntu keep asking for my gmail password?
64196
Change user associated with Google Drive account (OSX) when old account does not exist
134993
My name includes space - How do I enter my username when typing command?
125458
How can I send email to user that is not logged in since 30 days?
1631
How can I change displayed name as sender?
136282
What characters should I use or not use in usernames on Linux?