PayPal Payment Gateway Integration

There are lot of web sites which explain how we can integrate PayPal payment gateway with  our web site. Sometimes those explanations make  confuses us and it is difficult to think what is  the good method .

In this article I explain some reliable secure method to integrate PayPal with our site. I have used PayPal API credentials method for integrating process.

First you need to create a sandbox account from this URL. After that you have to create two accounts for business and personal. These accounts help us to test future transactions.

You can use personal account’s dummy test credit card details to perform the test transactions through sandbox.

There is a tab called “API credentials” in business account sections. These credentials (signature, username, and password) are used to call to PayPal payment gateway from our site.

As a  second step, you can generate appropriate code files through this URL.

Above Integration wizard gives this NVPAPICaller class file. Add that file your  project. Check Appendix 1 ,bottom of the article for code of NVPAPICaller class. we use that class file's method for calling Paypal payment gateway.

I have written code in PayPal button’s  click event (Check out page ) as in  Appendix 2 . 

Once user click Paypal button , user is redirected to Paypal site as below image.

Appendix 2's  PayPal button’s  click event code explanation:
This code is used to set our API  details of our Paypal account.

NVPAPICaller test = new NVPAPICaller(OrganizationDetails.PaypalAPIUsername,OrganizationDetails.PaypalAPIPassword,OrganizationDetails.PaypalAPISignature);

Through this code we send request to Paypal with our payment details.

ret = test.MarkExpressCheckout(amt, shipToName, shipToStreet, shipToStreet2,

                                shipToCity, shipToState, shipToZip, shipToCountryCode,ref token, ref retMsg);

If Paypal respond is success ,  then user is directed to Paypal site. Mean while Paypal sends us a token. We need to keep it in session variable. That will be used in next step. 

if (ret)

{

          Session["token"] = token;

          Response.Redirect(retMsg);

}

else

{

         Response.Redirect("APIError.aspx?" + retMsg);

}

Successfully paid payments are redirected to Thank you page of our site. We can set success and unsuccessful URL in our method which is in  the class called NVPAPICaller(Appendix 1). Check Appendix 3 code of it.

string returnURL = ConfigurationManager.AppSettings["SuccessURL"].ToString();

string cancelURL = ConfigurationManager.AppSettings["FailedURL"].ToString();

NVPCodec encoder = new NVPCodec();

encoder["METHOD"] = "SetExpressCheckout";

encoder["RETURNURL"] = returnURL;

encoder["CANCELURL"] = cancelURL;

encoder["AMT"] = amt;

encoder["PAYMENTACTION"] = "Sale";

encoder["CURRENCYCODE"] = "AUD";

       

Appendix 4's  Thank you page code explanation:

In  our site's thank you page, I have written code to confirm payment. For that we have to use “token” which used in previous page.Thank you page full code can be seen in Appendix 4.

string token = Session["token"].ToString();

bool ret = test.GetShippingDetails(token, ref payerId, ref shippingAddress, ref retMsg);

Above method return payer id. Payer id and token  is used to confirm the payment as below.

ret = test.ConfirmPayment(finalPaymentAmount, token, payerId, ref decoder, ref retMsg);

Successfully payments  are returned transaction id and other useful informations.

Session["PaypalTransactionID"] = decoder["TRANSACTIONID"];

I would think this article help you to integrate Paypal payment gateway with your site.

Appendix 1 
C# code for NVPAPICaller class:

using System;

using System.Collections;

using System.Collections.Specialized;

using System.IO;

using System.Net;

using System.Text;

using System.Data;

using System.Configuration;

using System.Web;

/// <summary>

/// Summary description for NVPAPICaller

/// </summary>

public class NVPAPICaller

{

    public NVPAPICaller(string PaypalAPIUserName, string

        PaypalAPIPassword, string PaypaAPISignature)

    {

        APIUsername = PaypalAPIUserName;

        APIPassword = PaypalAPIPassword;

        APISignature = PaypaAPISignature;

    }

    //private static readonly ILog log = LogManager.GetLogger(typeof(NVPAPICaller));

      

    private string pendpointurl = "https://api-3t.paypal.com/nvp";

    private const string CVV2 = "CVV2";

    //Flag that determines the PayPal environment (live or sandbox)

    private const bool bSandbox =true;

   

  

    private const string SIGNATURE = "SIGNATURE";

    private const string PWD = "PWD";

    private const string ACCT = "ACCT";

    //Replace <API_USERNAME> with your API Username

    //Replace <API_PASSWORD> with your API Password

    //Replace <API_SIGNATURE> with your Signature

    public string APIUsername ;

    private string APIPassword;

    private string APISignature ;

    private string Subject = "";

       private string BNCode = "PP-ECWizard";

    //HttpWebRequest Timeout specified in milliseconds

    private const int Timeout = 5000;

    private static readonly string[] SECURED_NVPS = new string[] { ACCT, CVV2, SIGNATURE, PWD };

    /// <summary>

    /// Sets the API Credentials

    /// </summary>

    /// <param name="Userid"></param>

    /// <param name="Pwd"></param>

    /// <param name="Signature"></param>

    /// <returns></returns>

    public void SetCredentials(string Userid, string Pwd, string Signature)

    {

        APIUsername = Userid;

        APIPassword = Pwd;

        APISignature = Signature;

    }

    /// <summary>

    /// ShortcutExpressCheckout: The method that calls SetExpressCheckout API

    /// </summary>

    /// <param name="amt"></param>

    /// <param ref name="token"></param>

    /// <param ref name="retMsg"></param>

    /// <returns></returns>

    public bool ShortcutExpressCheckout(string amt, ref string token, ref string retMsg)

    {

              string host = "www.paypal.com";

              if (bSandbox)

              {

                     pendpointurl = "https://api-3t.sandbox.paypal.com/nvp";

                     host = "www.sandbox.paypal.com";

              }

        string returnURL = ConfigurationManager.AppSettings["SuccessURL"].ToString();

        string cancelURL = ConfigurationManager.AppSettings["FailedURL"].ToString();

        NVPCodec encoder = new NVPCodec();

        encoder["METHOD"] = "SetExpressCheckout";

        encoder["RETURNURL"] = returnURL;

        encoder["CANCELURL"] = cancelURL;

        encoder["Amt"] = amt;

        //encoder["PAYMENTACTION"] = "Sale";

        //encoder["CURRENCYCODE"] = "USD";

       // encoder["PAYMENTREQUEST_0_AMT"] = amt;

     //   encoder["PAYMENTREQUEST_0_CURRENCYCODE"] = "AUD";

     //   encoder["PAYMENTREQUEST_0_DESC"] = "dsds dss";

        encoder["CURRENCYCODE"] = "AUD";

       // encoder["SOLUTIONTYPE"] = "Sole";

        string pStrrequestforNvp = encoder.Encode();

        string pStresponsenvp = HttpCall(pStrrequestforNvp);

        NVPCodec decoder = new NVPCodec();

        decoder.Decode(pStresponsenvp);

        string strAck = decoder["ACK"].ToLower();

        if (strAck != null && (strAck == "success" || strAck == "successwithwarning"))

        {

            token = decoder["TOKEN"];

            string ECURL = "https://" + host + "/cgi-bin/webscr?cmd=_express-checkout" + "&token=" + token + "&useraction=commit";

            retMsg = ECURL;

            return true;

        }

        else

        {

            retMsg = "ErrorCode=" + decoder["L_ERRORCODE0"] + "&" +

                "Desc=" + decoder["L_SHORTMESSAGE0"] + "&" +

                "Desc2=" + decoder["L_LONGMESSAGE0"];

            return false;

        }

    }

    /// <summary>

    /// MarkExpressCheckout: The method that calls SetExpressCheckout API, invoked from the

    /// Billing Page EC placement

    /// </summary>

    /// <param name="amt"></param>

    /// <param ref name="token"></param>

    /// <param ref name="retMsg"></param>

    /// <returns></returns>

    public bool MarkExpressCheckout(string amt,

                        string shipToName, string shipToStreet, string shipToStreet2,

                        string shipToCity, string shipToState, string shipToZip,

                        string shipToCountryCode,ref string token, ref string retMsg)

    {

              string host = "www.paypal.com";

              if (bSandbox)

              {

                     pendpointurl = "https://api-3t.sandbox.paypal.com/nvp";

                     host = "www.sandbox.paypal.com";

              }

         string returnURL = ConfigurationManager.AppSettings["SuccessURL"].ToString();

        string cancelURL = ConfigurationManager.AppSettings["FailedURL"].ToString();

        NVPCodec encoder = new NVPCodec();

        encoder["METHOD"] = "SetExpressCheckout";

        encoder["RETURNURL"] = returnURL;

        encoder["CANCELURL"] = cancelURL;

        encoder["AMT"] = amt;

        encoder["PAYMENTACTION"] = "Sale";

        encoder["CURRENCYCODE"] = "AUD";

       // encoder["DESC"] = "Payment";

        encoder["VERSION"] = "52";

        //Optional Shipping Address entered on the merchant site

        encoder["SHIPTONAME"] = shipToName;

        encoder["SHIPTOSTREET"] = shipToStreet;

        encoder["SHIPTOSTREET2"] = shipToStreet2;

        encoder["SHIPTOCITY"] = shipToCity;

        encoder["SHIPTOSTATE"] = shipToState;

        encoder["SHIPTOZIP"] = shipToZip;

        encoder["SHIPTOCOUNTRYCODE"] = shipToCountryCode;

      

        string pStrrequestforNvp = encoder.Encode();

        string pStresponsenvp = HttpCall(pStrrequestforNvp);

        NVPCodec decoder = new NVPCodec();

        decoder.Decode(pStresponsenvp);

        string strAck = decoder["ACK"].ToLower();

        if (strAck != null && (strAck == "success" || strAck == "successwithwarning"))

        {

         

            token = decoder["TOKEN"];

            string ECURL = "https://" + host + "/cgi-bin/webscr?cmd=_express-checkout" + "&token=" + token + "&useraction=commit";

            retMsg = ECURL;

            return true;

        }

        else

        {

            retMsg = "ErrorCode=" + decoder["L_ERRORCODE0"] + "&" +

                "Desc=" + decoder["L_SHORTMESSAGE0"] + "&" +

                "Desc2=" + decoder["L_LONGMESSAGE0"];

            return false;

        }

    }

    /// <summary>

    /// GetShippingDetails: The method that calls SetExpressCheckout API, invoked from the

    /// Billing Page EC placement

    /// </summary>

    /// <param name="token"></param>

    /// <param ref name="retMsg"></param>

    /// <returns></returns>

    public bool GetShippingDetails(string token, ref string PayerId, ref string ShippingAddress, ref string retMsg)

    {

              if (bSandbox)

              {

                     pendpointurl = "https://api-3t.sandbox.paypal.com/nvp";

              }

             

        NVPCodec encoder = new NVPCodec();

        encoder["METHOD"] = "GetExpressCheckoutDetails";

        encoder["TOKEN"] = token;

      

        string pStrrequestforNvp = encoder.Encode();

        string pStresponsenvp = HttpCall( pStrrequestforNvp );

        NVPCodec decoder = new NVPCodec();

        decoder.Decode( pStresponsenvp );

        string strAck = decoder["ACK"].ToLower();

        if (strAck != null && (strAck == "success" || strAck == "successwithwarning"))

        {

            ShippingAddress = "<table><tr>";

            ShippingAddress += "<td> First Name </td><td>" + decoder["FIRSTNAME"] + "</td></tr>";

            ShippingAddress += "<td> Last Name </td><td>" + decoder["LASTNAME"] + "</td></tr>";

            ShippingAddress += "<td colspan='2'> Shipping Address</td></tr>";

            ShippingAddress += "<td> Name </td><td>" + decoder["PAYMENTREQUEST_0_SHIPTONAME"] + "</td></tr>";

            ShippingAddress += "<td> Street1 </td><td>" + decoder["PAYMENTREQUEST_0_SHIPTOSTREET"] + "</td></tr>";

            ShippingAddress += "<td> Street2 </td><td>" + decoder["PAYMENTREQUEST_0_SHIPTOSTREET2"] + "</td></tr>";

            ShippingAddress += "<td> City </td><td>" + decoder["PAYMENTREQUEST_0_SHIPTOCITY"] + "</td></tr>";

            ShippingAddress += "<td> State </td><td>" + decoder["PAYMENTREQUEST_0_SHIPTOSTATE"] + "</td></tr>";

            ShippingAddress += "<td> Zip </td><td>" + decoder["PAYMENTREQUEST_0_SHIPTOZIP"] + "</td>";

            ShippingAddress += "</tr>";

            PayerId = decoder["PAYERID"].ToString();

            return true;

        }

        else

        {

            retMsg = "ErrorCode=" + decoder["L_ERRORCODE0"] + "&" +

                "Desc=" + decoder["L_SHORTMESSAGE0"] + "&" +

                "Desc2=" + decoder["L_LONGMESSAGE0"];

            return false;

        }

    }

    /// <summary>

    /// ConfirmPayment: The method that calls SetExpressCheckout API, invoked from the

    /// Billing Page EC placement

    /// </summary>

    /// <param name="token"></param>

    /// <param ref name="retMsg"></param>

    /// <returns></returns>

    public bool ConfirmPayment(string finalPaymentAmount, string token, string PayerId, ref NVPCodec decoder, ref string retMsg )

    {

              if (bSandbox)

              {

                     pendpointurl = "https://api-3t.sandbox.paypal.com/nvp";

              }

             

        NVPCodec encoder = new NVPCodec();

        encoder["METHOD"] = "DoExpressCheckoutPayment";

        encoder["TOKEN"] = token;

        encoder["PAYMENTACTION"] = "Sale";

       // encoder["PAYMENTREQUEST_0_PAYMENTACTION"] = "Sale";

        encoder["PAYERID"] = PayerId;

        encoder["AMT"] = finalPaymentAmount;

       // encoder["PAYMENTREQUEST_0_AMT"] = finalPaymentAmount;

              //encoder["PAYMENTREQUEST_0_CURRENCYCODE"] = "AUD";

        encoder["CURRENCYCODE"] = "AUD";

        string pStrrequestforNvp = encoder.Encode();

        string pStresponsenvp = HttpCall(pStrrequestforNvp);

        decoder = new NVPCodec();

        decoder.Decode(pStresponsenvp);

        string strAck = decoder["ACK"].ToLower();

        if (strAck != null && (strAck == "success" || strAck == "successwithwarning"))

        {

                  return true;

        }

        else

        {

            retMsg = "ErrorCode=" + decoder["L_ERRORCODE0"] + "&" +

                "Desc=" + decoder["L_SHORTMESSAGE0"] + "&" +

                "Desc2=" + decoder["L_LONGMESSAGE0"];

            return false;

        }

    }

    /// <summary>

    /// HttpCall: The main method that is used for all API calls

    /// </summary>

    /// <param name="NvpRequest"></param>

    /// <returns></returns>

    public string HttpCall(string NvpRequest) //CallNvpServer

    {

        string url = pendpointurl;

        //To Add the credentials from the profile

        string strPost = NvpRequest + "&" + buildCredentialsNVPString();

              strPost = strPost + "&BUTTONSOURCE=" + HttpUtility.UrlEncode( BNCode );

        HttpWebRequest objRequest = (HttpWebRequest)WebRequest.Create(url);

        objRequest.Timeout = Timeout;

        objRequest.Method = "POST";

        objRequest.ContentLength = strPost.Length;

        try

        {

            using (StreamWriter myWriter = new StreamWriter(objRequest.GetRequestStream()))

            {

                myWriter.Write(strPost);

            }

        }

        catch (Exception e)

        {

            /*

            if (log.IsFatalEnabled)

            {

                log.Fatal(e.Message, this);

            }*/

        }

        //Retrieve the Response returned from the NVP API call to PayPal

        HttpWebResponse objResponse = (HttpWebResponse)objRequest.GetResponse();

        string result;

        using (StreamReader sr = new StreamReader(objResponse.GetResponseStream()))

        {

            result = sr.ReadToEnd();

        }

        //Logging the response of the transaction

        /* if (log.IsInfoEnabled)

         {

             log.Info("Result :" +

                       " Elapsed Time : " + (DateTime.Now - startDate).Milliseconds + " ms" +

                      result);

         }

         */

        return result;

    }

    /// <summary>

    /// Credentials added to the NVP string

    /// </summary>

    /// <param name="profile"></param>

    /// <returns></returns>

    private string buildCredentialsNVPString()

    {

        NVPCodec codec = new NVPCodec();

        if (!IsEmpty(APIUsername))

            codec["USER"] = APIUsername;

        if (!IsEmpty(APIPassword))

            codec[PWD] = APIPassword;

        if (!IsEmpty(APISignature))

            codec[SIGNATURE] = APISignature;

        if (!IsEmpty(Subject))

            codec["SUBJECT"] = Subject;

        codec["VERSION"] = "2.3";

        return codec.Encode();

    }

    /// <summary>

    /// Returns if a string is empty or null

    /// </summary>

    /// <param name="s">the string</param>

    /// <returns>true if the string is not null and is not empty or just whitespace</returns>

    public static bool IsEmpty(string s)

    {

        return s == null || s.Trim() == string.Empty;

    }

}

public sealed class NVPCodec : NameValueCollection

{

    private const string AMPERSAND = "&";

    private const string EQUALS = "=";

    private static readonly char[] AMPERSAND_CHAR_ARRAY = AMPERSAND.ToCharArray();

    private static readonly char[] EQUALS_CHAR_ARRAY = EQUALS.ToCharArray();

    /// <summary>

    /// Returns the built NVP string of all name/value pairs in the Hashtable

    /// </summary>

    /// <returns></returns>

    public string Encode()

    {

        StringBuilder sb = new StringBuilder();

        bool firstPair = true;

        foreach (string kv in AllKeys)

        {

            string name = HttpUtility.UrlEncode(kv);

            string value = HttpUtility.UrlEncode(this[kv]);

            if (!firstPair)

            {

                sb.Append(AMPERSAND);

            }

            sb.Append(name).Append(EQUALS).Append(value);

            firstPair = false;

        }

        return sb.ToString();

    }

    /// <summary>

    /// Decoding the string

    /// </summary>

    /// <param name="nvpstring"></param>

    public void Decode(string nvpstring)

    {

        Clear();

        foreach (string nvp in nvpstring.Split(AMPERSAND_CHAR_ARRAY))

        {

            string[] tokens = nvp.Split(EQUALS_CHAR_ARRAY);

            if (tokens.Length >= 2)

            {

                string name = HttpUtility.UrlDecode(tokens[0]);

                string value = HttpUtility.UrlDecode(tokens[1]);

                Add(name, value);

            }

        }

    }

    #region Array methods

    public void Add(string name, string value, int index)

    {

        this.Add(GetArrayName(index, name), value);

    }

    public void Remove(string arrayName, int index)

    {

        this.Remove(GetArrayName(index, arrayName));

    }

    /// <summary>

    ///

    /// </summary>

    public string this[string name, int index]

    {

        get

        {

            return this[GetArrayName(index, name)];

        }

        set

        {

            this[GetArrayName(index, name)] = value;

        }

    }

    private static string GetArrayName(int index, string name)

    {

        if (index < 0)

        {

            throw new ArgumentOutOfRangeException("index", "index can not be negative : " + index);

        }

        return name + index;

    }

    #endregion

}

  

Appendix 2 
Checkout page:

  #region Paypal paymentGatway events and methods

        protected void imgpaypal_Click(object sender, ImageClickEventArgs e)

        {

            PaypalCall();    

        }

        public void PaypalCall()

        {

            NVPAPICaller test = new NVPAPICaller(OrganizationDetails.PaypalAPIUsername,OrganizationDetails.PaypalAPIPassword,OrganizationDetails.PaypalAPISignature);

            string retMsg = "";

            string token = "";

            SaveDatailinClass();

           

           decimal total = (from shoppingitem in shoppingCartCollection

                                 select shoppingitem.UnitPrice).Sum();

           if (total >= 10000)

           {

               total = total + total *0.02M;

           }

           HttpContext.Current.Session["payment_amt"] = total;

            bool ret;

           

            if (Session["payment_amt"] != null)

            {

              

                string amt = Session["payment_amt"].ToString();

                //Optional Shipping Address entered on the merchant site

                string shipToName = ShopperDetails.FirstName;

                string shipToStreet =ShopperDetails.Address1;

                string shipToStreet2 = ShopperDetails.Address1;

                string shipToCity = ShopperDetails.City;

                string shipToState = ShopperDetails.State;

                string shipToZip = ShopperDetails.Zip;

                string shipToCountryCode = ShopperDetails.Country;

                ret = test.MarkExpressCheckout(amt, shipToName, shipToStreet, shipToStreet2,

                                shipToCity, shipToState, shipToZip, shipToCountryCode,

                                ref token, ref retMsg);

                if (ret)

                {

                    Session["token"] = token;

                    Response.Redirect(retMsg);

                }

                else

                {

                    Response.Redirect("APIError.aspx?" + retMsg);

                }

            }

            else

            {

                Response.Redirect("APIError.aspx?ErrorCode=AmtMissing");

            }

        }

Appendix 3 

public bool MarkExpressCheckout(string amt,

                        string shipToName, string shipToStreet, string shipToStreet2,

                        string shipToCity, string shipToState, string shipToZip,

                        string shipToCountryCode,ref string token, ref string retMsg)

    {

              string host = "www.paypal.com";

              if (bSandbox)

              {

                     pendpointurl = "https://api-3t.sandbox.paypal.com/nvp";

                     host = "www.sandbox.paypal.com";

              }

         string returnURL = ConfigurationManager.AppSettings["SuccessURL"].ToString();

        string cancelURL = ConfigurationManager.AppSettings["FailedURL"].ToString();

        NVPCodec encoder = new NVPCodec();

        encoder["METHOD"] = "SetExpressCheckout";

        encoder["RETURNURL"] = returnURL;

        encoder["CANCELURL"] = cancelURL;

        encoder["AMT"] = amt;

        encoder["PAYMENTACTION"] = "Sale";

        encoder["CURRENCYCODE"] = "AUD";

       // encoder["DESC"] = "Payment";

        encoder["VERSION"] = "52";

        //Optional Shipping Address entered on the merchant site

        encoder["SHIPTONAME"] = shipToName;

        encoder["SHIPTOSTREET"] = shipToStreet;

        encoder["SHIPTOSTREET2"] = shipToStreet2;

        encoder["SHIPTOCITY"] = shipToCity;

        encoder["SHIPTOSTATE"] = shipToState;

        encoder["SHIPTOZIP"] = shipToZip;

        encoder["SHIPTOCOUNTRYCODE"] = shipToCountryCode;

      

        string pStrrequestforNvp = encoder.Encode();

        string pStresponsenvp = HttpCall(pStrrequestforNvp);

        NVPCodec decoder = new NVPCodec();

        decoder.Decode(pStresponsenvp);

        string strAck = decoder["ACK"].ToLower();

        if (strAck != null && (strAck == "success" || strAck == "successwithwarning"))

        {

         

            token = decoder["TOKEN"];

            string ECURL = "https://" + host + "/cgi-bin/webscr?cmd=_express-checkout" + "&token=" + token + "&useraction=commit";

            retMsg = ECURL;

            return true;

        }

        else

        {

            retMsg = "ErrorCode=" + decoder["L_ERRORCODE0"] + "&" +

                "Desc=" + decoder["L_SHORTMESSAGE0"] + "&" +

                "Desc2=" + decoder["L_LONGMESSAGE0"];

            return false;

        }

    }

Appendix 4 
Thank you page:

     protected void Page_Load(object sender, EventArgs e)

     {

            NVPAPICaller test = new NVPAPICaller(OrganizationDetails.PaypalAPIUsername, OrganizationDetails.PaypalAPIPassword, OrganizationDetails.PaypalAPISignature);

         

            string payerId = "";

            string shippingAddress = "";

            string retMsg = "";

            NVPCodec decoder = null;

            string finalPaymentAmount = Session["payment_amt"].ToString();

            string token = Session["token"].ToString();

            bool ret = test.GetShippingDetails(token, ref payerId, ref shippingAddress, ref retMsg);

            if (ret)

            {

                Session["payerId"] = payerId;

              //  Response.Write(shippingAddress);

                ret = test.ConfirmPayment(finalPaymentAmount, token, payerId, ref decoder, ref retMsg);

                if (ret)

                {

                    // Unique transaction ID of the payment. Note:  If the PaymentAction of the request was Authorization or Order, this value is your AuthorizationID for use with the Authorization & Capture APIs.

                    Session["PaypalTransactionID"] = decoder["TRANSACTIONID"];

                    imgLogo.ImageUrl = OrganizationDetails.LogoPath;

                    litLogoText.Text = string.Format("<div class='{0}'>{1}</div>", OrganizationDetails.LogoTextCSSClass, OrganizationDetails.LogoText);

                    litSubject.Text = OrganizationDetails.LogoSubjectText;

                    StringBuilder mytext = new StringBuilder();

                    mytext.Append(string.Format("<div class='{0}'>{1}</div>", OrganizationDetails.LogoTextCSSClass, "Thank you for your payment."));

                    mytext.Append(string.Format("</br><p> Your Paypal Transaction ID  : {0} </p>", Session["PaypalTransactionID"].ToString()));

                    litBody.Text = mytext.ToString();

                    checkout checkoutpage = new checkout();

                    checkoutpage.SendEmailToAdmin();

                    checkoutpage.SendEmailToClient();

                   

                }

                else

                {

                    Response.Redirect("APIError.aspx?" + retMsg);

                }

            }

            else

            {

                Response.Redirect("APIError.aspx?" + retMsg);

            }

        }