ขอวิธีแก้ พอดีส่งอีเมลออก ด้วยภาษาไทยแต่กลายเป็น ????? เมื่อได้รับอีเมล รบกวนช่วยทีครับ

using System;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.Configuration;
using System.Web.Mail;

public partial class KACEEBEST : System.Web.UI.Page
{
    
    protected void Page_Load(object sender, EventArgs e)
    {

    }
    protected void btnSend_Click(object sender, EventArgs e)
    {
        MailMessage myMail = new MailMessage();

        myMail.BodyFormat = MailFormat.Html;
        myMail.BodyEncoding = MailEncoding.
        myMail.To = "[email protected]";
        myMail.From = "<" + this.txtFromEmail.Text.ToString() + ">" + this.txtFromName.Text.ToString();
        myMail.Bcc = this.txtFromEmail.Text;
        myMail.Subject = "Thank for Subscribe KACEE ขอบคุณครับ";
        myMail.Body = "Subscribe E-Newsletter From Website www.kaceebest.com ขอบคุณครับ";
        SmtpMail.Send(myMail);
		

        string strSMTP = "mail.kaceebest.com";
        string cdoSendUsingPort = "2";
        string cdoBasic = "1";
        string UserName = "[email protected]";
        string Password = "password";

        myMail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpserver", strSMTP);
        myMail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpserverport", 25);
        myMail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusing", cdoSendUsingPort);
        myMail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", cdoBasic);
        myMail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusername", UserName);
        myMail.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendpassword", Password);

        SmtpMail.SmtpServer = strSMTP;
        SmtpMail.Send(myMail);

        myMail = null;

        Page.ClientScript.RegisterStartupScript(Page.GetType(), "testAlert", "<script language=javascript>alert('Send Mail Complete');</script>");
    }

}

message.BodyEncoding =  System.Text.Encoding.UTF8;

string strSubject = "=?UTF-8?B?".base64_encode("ส่งอีเมล์ภาษาไทย ด้วย php ทดสอบชื่อเรื่องภาษาไทย")."?=";