using System;

using System.Globalization;

using System.Text;

using System.Collections.Generic;

using System.Collections;

using System.Linq;

public class Program

{

    public class EmailComparison

    {

        public string originalEmail;

        public string formattedEmail;

    }

    public static void Main()

    {

        //Console.WriteLine(RemoveDiacritics("kurumsal.iletisim@kocsistem.com.tr").ToUpper());

        TestMethod("kurumsal.iletisim@kocsistem.com.tr");

        TestMethod("erinc.erenksoy@kocsistem.com.tr");

    }

    public static void TestMethod(string smtp)

    {

        var emailList = new List<string>();

        var comparisonList = new List<EmailComparison>();

        emailList.Add("Kurumsal.Iletisim@kocsistem.com.tr");

        emailList.Add("erinc.erensoy@kocsistem.com.tr");

        var smtpRemovedDiactrics = RemoveDiacritics(smtp).ToUpper();

        for(var II=0; II<emailList.Count;II++)

        {

            var comparisonObject = new EmailComparison();

            comparisonObject.originalEmail = emailList[II];

            comparisonObject.formattedEmail = RemoveDiacritics(emailList[II]).ToUpper();

            comparisonList.Add(comparisonObject);

        }

        var foundComparisonObject = comparisonList.Where((v=>v.formattedEmail==smtpRemovedDiactrics)).FirstOrDefault();

        if(foundComparisonObject == null)

        {

            Console.WriteLine("Not Found");

        }

        else

        {

            Console.WriteLine("Found:"+foundComparisonObject.originalEmail);

        }

    }

    public static string RemoveDiacritics(string text)

{

    Encoding srcEncoding = Encoding.UTF8;

    Encoding destEncoding = Encoding.GetEncoding(1252); // Latin alphabet

​

    text = destEncoding.GetString(Encoding.Convert(srcEncoding, destEncoding, srcEncoding.GetBytes(text)));

​

    string normalizedString = text.Normalize(NormalizationForm.FormD);

    StringBuilder result = new StringBuilder();

​

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

    {

        if (!CharUnicodeInfo.GetUnicodeCategory(normalizedString[i]).Equals(UnicodeCategory.NonSpacingMark))

        {

            result.Append(normalizedString[i]);

        }

    }

​

    return result.ToString();

}

}

​

​