using System;   

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("How many records you want to create?");

        var numberOfEmails=Convert.ToInt32(Console.ReadLine());

        Console.WriteLine("What is the email you want to generate aliases?");

        var email=Console.ReadLine().ToString();

        var emailParts=email.Split('@').ToList();

        var last=emailParts.LastOrDefault();

        if(emailParts.Count>=2){

            var data=new List<string>();

            for(var i=0;i<=numberOfEmails;i++)

            {

                var first=emailParts.FirstOrDefault();

                if(!string.IsNullOrEmpty(first)){

                    first+=$"+Test{i}";

                }

                data.Add($"{first}@{last}");

            }

            data.Dump();

        }

    }

}