Sending mail with attachments programmatically in ASP.NET

Question

I am dynamically generating a number of different types of files based upon a GridView in ASP.NET - an Excel spreadsheet and a HTML file. I am doing so using this code (this is just for the Excel spreadsheet):

  Response.Clear();
  Response.AddHeader("content-disposition", "attachment;filename=InvoiceSummary" + Request.QueryString["id"] + ".xls");
  Response.Charset = "";

  Response.ContentType = "application/vnd.xls";
  System.IO.StringWriter stringWrite = new System.IO.StringWriter();
  System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);
  contents.RenderControl(htmlWrite);
  //GridView1.RenderControl(htmlWrite);
  Response.Write(stringWrite.ToString());
  Response.End();

I would like to give users the options of emailing the generated file as an attachment to either an email address they specify or one linked with their account on the database. But I don't want the user to have to save the file, then attach it in a form - I'd like to automatically attach the generated file. Is this possible, and how easy is it?

Of course, I'll be using the System.Net.Mail class to send mail...if it's possible anyway!

Answer 1

You might be able to create System.Net.Mail.Attachment from string then send out the mail as normal.

var m = new System.Net.Mail.MailMessage(from, to, subject, body);
var a = System.Net.Mail.Attachment.CreateAttachmentFromString(stringWrite.ToString(), "application/vnd.xls");
m.Attachments.Add(a);

Answer 2

    protected void btnSend_OnClick(object sender, EventArgs e)
    {
        MailMessage mail = new MailMessage();
        byte[] data = new byte[1024];
        MemoryStream stream = new MemoryStream(data);
        Attachment attach = new Attachment(stream, "Attachment file name");
        mail.Attachments.Add(attach);
        new SmtpClient().Send(mail);
    }

Answer 3

You can save the file contents into a byte array and then do this:

Creating In-Memory Mail Attachments

Answer 4

Here is an working example of what I mentioned earlier, there is a little extra logic in the code to parse the GridView to a Table.

        //Table to store our GridView Data
        Table table = new Table();

        //Parse our GridView into Table, stored in a StringBuilder
        StringBuilder sb = new StringBuilder();
        using (StringWriter sw = new StringWriter(sb))
        {
            using (HtmlTextWriter htw = new HtmlTextWriter(sw))
            {
                //  header
                if (GridView1.HeaderRow != null)
                {
                    table.Rows.Add(GridView1.HeaderRow);
                }

                //  details
                foreach (GridViewRow row in GridView1.Rows)
                {
                    table.Rows.Add(row);
                }

                //  footer
                if (GridView1.FooterRow != null)
                {
                    table.Rows.Add(GridView1.FooterRow);
                }

                //  render table
                table.RenderControl(htw);
            }
        }


        using (MemoryStream memoryStream = new MemoryStream())
        {
            using (StreamWriter writer = new StreamWriter(memoryStream))
            {
                //Convert StringBuilder to MemoryStream
                writer.Write(sb.ToString());
                writer.Flush();

                //Create Message
                MailMessage message = new MailMessage();
                message.To.Add(new MailAddress("you@address.com", "You"));
                message.From = new MailAddress("me@address.com", "Me");
                message.Subject = "The Subject";

                //Create Attachment
                Attachment attachment = new Attachment(memoryStream, "InvoiceSummary.xls", "application/vnd.xls");

                //Attach Attachment to Email
                message.Attachments.Add(attachment);

                //Open SMTP connection to server and send
                SmtpClient smtp = new SmtpClient();
                smtp.Port = 25;
                smtp.Send(message);
            }
        }