forbid users to use "@" inside the username
Some users register with their emails or they think they must put "@" before the username, generating usernames like:
"username@gmail.com"
OR
"@Username"
In the last step you can see how federated identities looks like...it's pretty confusing and messy if you ask me. I believe is very needed to prevent these behaviours avoiding the use of "@" in the username.
Edited by RebelCode