Question

i have to send mail with attachments.my code works only for files smaller than 4mb.
I have already checked everything on net but everyone suggest the same soolution.That is to change httpruntime attributes in webconfig which i have already done.

<httpRuntime maxRequestLength="10000" executionTimeout="1500"  />

i have changed everything that has “timeout” attribute in web config.Also made a change in KeepAlive in application configuration in IIS but even after doing all this changes the problem still remain in my application.everytime i try to upload files larger than 4mb the connection timeout after exactly 1.5 minutes.

Code in click event

protected void btnSend_Click(object sender, EventArgs e)
        {
            MailMessage msg = new MailMessage();
            SmtpClient smtp = new SmtpClient();
            string strFrom = txtFrom.Text;
            string strTo = txtTo.Text;
            string strSubject= ddlTemplate.SelectedItem.Text.ToString();
            string strBody =txtBody.Text;
            string strCC =txtCC.Text;
            string strBCC =txtBCC.Text;
            if (this.fuAttachments.HasFile)
            {
                Attachment at = new Attachment(fuAttachments.PostedFile.InputStream,fuAttachments.PostedFile.ContentType);

                at.ContentDisposition.FileName = this.fuAttachments.FileName;
                msg.Attachments.Add(at);


            }
           smtp.EnableSsl = true;

            msg.From = new MailAddress(strFrom);
            msg.To.Add(strTo);
            msg.Subject = strSubject;
            msg.Body = strBody;

            //smtp = new SmtpClient("localhost");
            //smtp.UseDefaultCredentials = true;

            try 
            {
                smtp.Send(msg);
            }
            catch (SmtpException Ex)
            {

                throw;
            } 

            if (msg.Attachments.Count > 0)
            {
                //Clear the attachments and delete the sessionid folder from tempFiles 
                msg.Attachments.Dispose();
            }

        }

Answer 1

I have found the culprit in my application.It is smtp client’s timeout property that was stopping the process after around 1.5minutes.Default value for this property is 100 seconds which i changed to 1500 seconds(1500000ms as this property takes values in ms) and successfully mailed with attachment.

smtp.Timeout = 1500000;

see this for more info.

by the way i tested it with 21mb attachment.