using System;

using System.Text.RegularExpressions;

​

public class Program

{

    public static void Main()

    {

        string email = "test-1.p46@ala-bala.somehost.somewhere.bg";

string regex = @"^([a-zA-Z0-9_\-][a-zA-Z0-9_\-\.]{0,49})" +

@"@(([a-zA-Z0-9][a-zA-Z0-9\-]{0,49}\.)+[a-zA-Z]{2,4})$";

bool valid = Regex.IsMatch(email, regex);

Console.WriteLine(valid);

    }

}