I use this
@\"^([\\w\\.\\-]+)@([\\w\\-]+)((\\.(\\w){2,3})+)$\"
regexp to validate the email
([\\w\\.\\-]+) - this is f
([\\w\\.\\-]+)
This regex works perfectly:
bool IsValidEmail(string email) { return Regex.IsMatch(email, @"^[\w!#$%&'*+\-/=?\^_`{|}~]+(\.[\w!#$%&'*+\-/=?\^_`{|}~]+)*@((([\-\w]+\.)+[a-zA-Z]{2,4})|(([0-9]{1,3}\.){3}[0-9]{1,3}))\z"); }