Question

I am generating an email via codebehind in C# in my asp.net application using the line below:

ClientScript.RegisterStartupScript(this.GetType(), "FormLoading", "window.open('mailto:[e-mail]?subject=Invoice for ABC Corp - " + ddlJobCode.SelectedItem.Text + " - Supporting Documentation', 'email');", true);

Is it possible to include an attachment programatically as well (if the user points to the attachment document via a browse button) ?

Answer 1

No I don’t think so… the mailto functionality is passed off by the browser to the default client. You have no other mechanism of talking to the client or even knowing if the mailto was even successful.

If you want to add an attachment you will most likely have to send the email on behalf of them and do it server side.

Edit: To do it server side you would need to post the page so that the Browse button pulls down the file server side and then you would need to construct the email and send it out via your own smtp server. Here is a quick code example, you will probably need to adapt it to work with your specific case:

In your server side OnClick handler:

protected void btnSendEmail_Click(object sender, EventArgs e)
{  
    // this will get the file from your asp:FileUpload control (browse button)
    HttpPostedFile file = (HttpPostedFile)(fuAttachment.PostedFile);
    if ((file != null) && (file.ContentLength > 0))
    {
        // You should probably check file size and extension types and whatever
        // other validation here as well
        byte[] uploadedFile = new byte[file.ContentLength];
        file.InputStream.Read(uploadedFile, 0, file.ContentLength);

        // Save the file locally
        int lastSlash = file.FileName.LastIndexOf('\\') + 1;
        string fileName = file.FileName.Substring(lastSlash,
            file.FileName.Length - lastSlash);

        string localSaveLocation = yourLocalPathToSaveFile + fileName;
        System.IO.File.WriteAllBytes(localSaveLocation, uploadedFile);

        try
        {
            // Create and send the email
            MailMessage msg = new MailMessage();
            msg.To = "[e-mail]";
            msg.From = "[e-mail]";
            msg.Subject = "Attachment Test";
            msg.Body = "Test Attachment";
            msg.Attachments.Add(new MailAttachment(localSaveLocation));

            // Don't forget you have to setup your SMTP settings
            SmtpMail.Send(msg);
        }
        finally
        {
            // make sure to clean up the file that was uploaded
            System.IO.File.Delete(localSaveLocation);
        }
    }
}