Hi,
Please check it is working fine. and it is very good.
String email_regx
="^([a-zA-Z]+(([a-zA-Z0-9]*)|((([^@]{0,}?)[a-zA-Z0-9]+){0,}))([@]{1})[a-zA-Z0-9]+(([.]{1})([a-zA-Z0-9]+)){1,2})$"
Main Validations:
1.Does Not allow special characters before @.
2.UserName must Not contain @.