Reroute email, C# - rextester

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;

namespace Rextester
{
    public class Program
    {
        private static bool overwriteEmailAddressWithTestEmailAddress = false;
        //private static bool overwriteEmailAddressWithTestEmailAddress = true;
        private static string TestEmailAddress = "cvoportal@gmail.com;buffskan@gmail.com;*@e.rainforestqa.com;*@outlookamusements.com";            
        private static string TestEmailDomains = "@example.com";
            
        public static void Main(string[] args)
        {
            //Your code goes here
            Console.WriteLine("1. {0}", RouteEmail("odukes@hotmail.com"));
            Console.WriteLine("2. {0}", RouteEmail("buffskan@gmail.com"));
            Console.WriteLine("3. {0}", RouteEmail("someone@example.com"));
            Console.WriteLine("4. {0}", RouteEmail("tester@e.rainforestqa.com"));
            Console.WriteLine("5. {0}", RouteEmail("employee@outlookamusements.com"));
        }
        
        private static string RouteEmail(string emailAddress)
        {
            //make sure email address is not empty
            if (string.IsNullOrEmpty(emailAddress))
            {
                throw new Exception("No Receipient Email Address Specified");
            }
            else if (emailAddress.IndexOf("@") <= -1)
            {
                throw new Exception("Invalid Email Address");
            }
            else
            {
                //check if we should forward to test email account.
                var emailAddressDomain = string.Concat("@", emailAddress.Split(new char[] { '@' })[1]);

if (!overwriteEmailAddressWithTestEmailAddress)
                {
                    //check if email contains domain that should be forwarded to test
                    if (TestEmailDomains.Contains((emailAddressDomain.ToLower().Trim())))
                    {
                        overwriteEmailAddressWithTestEmailAddress = true;
                    }
                }

//send to test email if in test mode or test domain matched
                if (overwriteEmailAddressWithTestEmailAddress)
                {
                    //overwrite with test email if set
                    var testEmailAddresses = TestEmailAddress.Trim().Replace(" ", "").Split(new char[] { ',', ';' });

//check an overwrite for real email and also check to allow test email domains e.g *@e.rainforestqa.com
                    if (!testEmailAddresses.Contains(emailAddress) && !testEmailAddresses.Contains("*" + emailAddressDomain))
                    {
                        emailAddress = testEmailAddresses[0];
                    }
                }
            }
            return emailAddress;
        }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,16 sec, absolute running time: 0,09 sec, cpu time: 0,09 sec, average memory usage: 14 Mb, average nr of threads: 3