C#

public class ClipboardMetafileHelper
   {
       [DllImport("user32.dll", EntryPoint = "OpenClipboard", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
       public static extern bool OpenClipboard(IntPtr hWnd);
       [DllImport("user32.dll", EntryPoint = "EmptyClipboard", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
       public static extern bool EmptyClipboard();
       [DllImport("user32.dll", EntryPoint = "SetClipboardData", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
       public static extern IntPtr SetClipboardData(int uFormat, IntPtr hWnd);
       [DllImport("user32.dll", EntryPoint = "GetClipboardData", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
       public static extern IntPtr GetClipboardData(int uFormat);
       [DllImport("user32.dll", EntryPoint = "CloseClipboard", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
       public static extern bool CloseClipboard();
       [DllImport("gdi32.dll", EntryPoint = "CopyEnhMetaFileA", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
       public static extern IntPtr CopyEnhMetaFile(IntPtr hemfSrc, IntPtr hNULL);
       [DllImport("gdi32.dll", EntryPoint = "DeleteEnhMetaFile", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
       public static extern bool DeleteEnhMetaFile(IntPtr hemfSrc);

       // Metafile mf is set to a state that is not valid inside this function.
       public static bool PutEnhMetafileOnClipboard(IntPtr hWnd, Metafile mf)
       {
           bool bResult = new bool();
           bResult = false;
           IntPtr hEMF = default(IntPtr);
           IntPtr hEMF2 = default(IntPtr);
           hEMF = mf.GetHenhmetafile();
           // invalidates mf
           if (!hEMF.Equals(new IntPtr(0)))
           {
               hEMF2 = CopyEnhMetaFile(hEMF, new IntPtr(0));
               if (!hEMF2.Equals(new IntPtr(0)))
               {
                   if (OpenClipboard(hWnd))
                   {
                       if (EmptyClipboard())
                       {
                           IntPtr hRes = default(IntPtr);
                           hRes = SetClipboardData(14, hEMF2);
                           // 14 == CF_ENHMETAFILE
                           bResult = hRes.Equals(hEMF2);
                           CloseClipboard();
                       }
                   }
               }
               DeleteEnhMetaFile(hEMF);
           }
           return bResult;
       }

       public static Image GetEnhMetafileFromClipboard(IntPtr hWnd)
       {
           OpenClipboard(hWnd);
           // IntPtr.Zero
           IntPtr hemf = GetClipboardData(14);
           // 14 == CF_ENHMETAFILE
           CloseClipboard();
           if (hemf != IntPtr.Zero)
           {
               Metafile mf = new Metafile(hemf, true);
               Bitmap b = new Bitmap(mf.Width, mf.Height);
               Graphics g = Graphics.FromImage(b);
               g.FillRectangle(Brushes.White, 0, 0, 1000, 1000);
               GraphicsUnit unit = GraphicsUnit.Millimeter;
               RectangleF rsrc = mf.GetBounds(ref unit);
               g.DrawImage(mf, new Rectangle(0, 0, mf.Width, mf.Height), rsrc, unit);
               return b;
           }


           return null;
       }


   }

public static SmtpClient create_SMTPClient(smtp_credentials smtpC)
        {
            var smtpClient = new SmtpClient();
            var smtpSection = (SmtpSection)ConfigurationManager.GetSection("system.net/mailSettings/smtp");
            if (smtpSection == null)
            {
                smtpClient.UseDefaultCredentials = false;
                smtpClient.DeliveryMethod = SmtpDeliveryMethod.Network;

<pre>
            var smtpCredentials = new System.Net.NetworkCredential() {
                UserName = smtpC.smtp_AccountName,
                Password = smtpC.smtp_Password
            };

            smtpClient.Credentials = smtpCredentials;
            smtpClient.Host = smtpC.smtp_ServerUrl;
            smtpClient.Port = smtpC.smtp_PortNumber;
            smtpClient.EnableSsl = smtpC.smtp_PortNumber == 587 ? true : false;
            smtpClient.Timeout = 250000;
        }

        // Shift the encryption level higher for gMail and others
        if (smtpClient.Port == 587)
            ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
        if (smtpClient.Port == 443)
            ServicePointManager.ServerCertificateValidationCallback += RemoteCertificateValidation_Callback;

        return smtpClient;
    }

    public static async Task<SendEmailCompletedEventArgs> sendEmailAsync(SmtpClient smtpClient, MailMessage message, int retryCount)
    {
        int currentTry = 0;
        while ((currentTry < retryCount))
        {
            try
            {
                await smtpClient.SendMailAsync(message);
                return new SendEmailCompletedEventArgs(null, false, null, currentTry);
            }
            catch (Exception ex)
            {
                currentTry++;
                if ((currentTry >= retryCount))
                {
                    return new SendEmailCompletedEventArgs(ex, true, null, currentTry);
                }
            }

        }

        //  Code should never reach here, but without this line you'll get a BC42105 warning:
        return new SendEmailCompletedEventArgs(null, true, null, currentTry);
    }</pre>