using System;

using System.Text.RegularExpressions;

public class Program

{

    public static void Main()

    {

        string[] emails = { "your_name1@gmail.com", "your.name2@yahoo.fr", "your.-_name3 @live.fr", "yourname4@hotmail.com","yourname5@gmail..com"};

        for(int i = 0; i < emails.Length; i++)

        {

​

            string pattern = @"^[a-z0-9A-Z.-_]+@[a-z]+\.[a-z]+$";

            bool ismatch = Regex.IsMatch(emails[i],pattern);

            Console.WriteLine(ismatch);

        }

    }

}