Answers and code snippets from ASP.NET projects (Webforms/MVC/Classic ASP)
return System.Text.RegularExpressions.Regex.IsMatch(email, @"^([\w-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([\w-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$");