validate an email address

ValidateEmailAddress.cs

string regex = @"\A(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?)\Z";
bool isEmail = Regex.IsMatch(emailString, regex, RegexOptions.IgnoreCase);

taken from http://stackoverflow.com/questions/16167983/best-regular-expression-for-email-validation-in-c-sharp

also see http://www.regular-expressions.info/email.html