Question

I am trying to send very large emails out, usually are in the range of 3 MB but can be larger. The problem is that our adsl line isn’t always very stable in terms of performance and our email hosting changed from a local solution to a remote one. This means that by using the normal C# send method I keep reaching the timeout reached exception. And I do not want to just increase the timeout. For a 3Mb email to upload succeed I need a timeout of 400 sec.

Following answer here
now I can get the emails to send via the local smtp service, but only if I don’t attach an attachment. If the attachment is in the area of 3Mb its fails outright. If it’s small it fails when I try to pull the email down with outlook.

I did remove the max file attachment size from the smtp service. Any other setting or so I could have gotten wrong?

And if it helps the pc that runs is smtp service is a virtual machine running win 2008 on a pc running win 7.

Answer 1

I fixed it using SendAsync, and used it as follows

I put all my emails in a Fifo list.
After I added new emails I remove one and try to send it.
This is my send function

public void Sender()
    {
        if (Globalcls.Message_list.Count == 0)
            return;
        SmtpClient client = new SmtpClient();
        client.Credentials = new System.Net.NetworkCredential(Globalcls.settings.username, Globalcls.settings.password);
        client.Port = Convert.ToInt32(Globalcls.settings.portS);


        client.Host = "smtp.xdsl.co.za";

        client.SendCompleted += new SendCompletedEventHandler(MailSendCallback);

        if (Globalcls.Message_list.Count > 0)
        {
            try
            {
                client.SendAsync(Globalcls.Message_list[0].msg, "1");


            }
            catch (Exception ex)
            {
                //do exception stuff here, only cut here to make post shorter
            }
        }

 static void MailSendCallback(object sender, AsyncCompletedEventArgs arg)
    {
        // oncomllete event for async send.
        if (arg.Error != null)
        {
            //mail did not send, here I do not remove it and increment an counter so  to delete a mail that keeps failing
        }
        else
        {

            Form1 frm1 = new Form1(); 
            frm1.que("email sent to " + Globalcls.projects[Globalcls.Message_list[0].project].name);
            frm1.Dispose();
            Globalcls.Message_list[0].msg.Dispose();
            foreach (string meh in Globalcls.Message_list[0].files)
                File.Delete(meh);
            Globalcls.Message_list.RemoveAt(0);
        }
        if (Globalcls.Message_list.Count > 0)
        {
            Form1 frm2 = new Form1();
            frm2.Sender();
            frm2.Dispose();
    }