Email going to junk folder in Outlook 2010

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Collections;
using System.Text;
using System.Configuration;
using System.Net.Mail;
using System.Data.SqlClient;
using System.Data;
using System.Net;
using System.Net.Mime;
using System.Text.RegularExpressions;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;

public partial class wwwbeta_Default : System.Web.UI.Page
{
    string EmailTo = string.Empty;
    string EmailFrom = string.Empty;
    string Body = string.Empty;
    string BCC = string.Empty;
    string Subject = string.Empty;

    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void btnsend_Click(object sender, EventArgs e)
    {
        EmailFrom = hdnEmail.Value;
        EmailTo = "reciever mail";
        Subject = "test";
        Body = hdnName.Value + " with EmailID " + hdnEmail.Value + " sends a message to you.<br /> The Message is following:" + hdnMessage.Value;
     

        String Result = SendMail(EmailFrom, EmailTo, BCC, Subject, Body, true);
        if (Result == "MailSent")
        {
            ScriptManager.RegisterStartupScript(this, GetType(), "MyScript", "showpopupAfterEmail();", true);
        }
    }
    public String SendMail(String MailFrom, String MailTo, String BCC, String Subject, String Body, Boolean IsHtmlBody)
    {
        MyMail.From = new MailAddress(MailFrom);
       
        String[] Tos = MailTo.Split(';');
        foreach (String To in Tos)
        {
            MyMail.To.Add(To);
        }
        if (BCC != "")
        {
            MyMail.Bcc.Add(BCC);
        }
        MyMail.Subject = Subject;
        MyMail.Body = Body;
       
      

        return SendMail();
    }
    String Output;
    MailMessage MyMail = new MailMessage();

    #region enum EnmMailResult
    public enum EnmMailResult
    {
        MailSent
    }
    #endregion
    #region String SendMail()
    String SendMail()
    {
        MyMail.Priority = MailPriority.Normal;
        try
        {
            SetSMTPCredentials(MyMail);
            Output = EnmMailResult.MailSent.ToString();
        }
        catch (Exception ex)
        {
            Output = ex.Message;
        }
        return Output;
    }
    #endregion

    public static void SetSMTPCredentials(MailMessage mailMsg)
    {
        String SMTPAddress = "";
        String SMTPUserName = "";
        String SMTPPassword = "";
        Int32 SMTPPort = 0;

        //Change Email format here for all emails
        StringBuilder sb = new StringBuilder();
        if (mailMsg.IsBodyHtml)
        
       
            sb.Append(mailMsg.Body);
            mailMsg.Body = sb.ToString();
      
        //End



        try
        {

            SMTPAddress = "address";
            SMTPUserName = "username";
            SMTPPassword = "password";
            SMTPPort = portno;



            SmtpClient smtpObj = new SmtpClient();
            smtpObj.Host = SMTPAddress;
            smtpObj.Port = SMTPPort;
            NetworkCredential netCred = new NetworkCredential(SMTPUserName, SMTPPassword);
            smtpObj.Credentials = netCred;
            // Execute stored procedure



            try
            {
                smtpObj.Send(mailMsg);

            }
            catch (Exception ex)
            {
                SMTPAddress = "address";
                SMTPUserName = "username";
                SMTPPassword = "password";
                SMTPPort = portno;
                smtpObj.Host = SMTPAddress;
                smtpObj.Port = SMTPPort;
                NetworkCredential netCred1 = new NetworkCredential(SMTPUserName, SMTPPassword);
                smtpObj.Credentials = netCred1;
                smtpObj.Send(mailMsg);
                System.Diagnostics.Debug.WriteLine(ex.Message);
            }
        }
        catch (Exception ex)
        {
            throw ex;
        }
        finally
        {

        }
    }
}