In this article I will discuss how to integrate the email functionality along with the attachment in a Asp.Net Application.

Getting Started:

Step 1: Create a web application.

Step 2: Take a File upload control and a Button as follows:

<asp:FileUpload ID="fuAttachment" runat="server" />

 <asp:Button ID="Button1" runat="server" Text="Send Mail" OnClick="Button1&#95;Click" />

Step 3: Now on click event ("Button1_Click") add the following code:

 using (MailMessage mm = new MailMessag("Sender's EmailAddress","Reciever's EmailAddress"))
  {
    mm.Subject = "Subject of the Email";
    mm.Body = "Main content of the Email";

    if(fuAttachment.HasFile)
     {
       string FileName = Path.GetFileName(fuAttachment.PostedFile.FileName);
       mm.Attachments.Add(new Attachment(fuAttachment.PostedFile.InputStream, FileName));
     }

    mm.IsBodyHtml = false;
    SmtpClient smtp = new SmtpClient();
    smtp.Host = "smtp.gmail.com";
    smtp.EnableSsl = true;
    NetworkCredential NetworkCred = new NetworkCredential("Sender's EmailAddress","Sender's   

   Password");
    smtp.UseDefaultCredentials = true;
    smtp.Credentials = NetworkCred;
    smtp.Port = 587;
    smtp.Send(mm);
    ClientScript.RegisterStartupScript(GetType(), "alert", "alert('Email sent.');", true);

  } 

In the above code, the following code will attach the file to the mail:

 if(fuAttachment.HasFile)
     {
       string FileName = Path.GetFileName(fuAttachment.PostedFile.FileName);
       mm.Attachments.Add(new Attachment(fuAttachment.PostedFile.InputStream, FileName));
     }

When the mail is sent the Following Line will show an alert of "Email Sent":

ClientScript.RegisterStartupScript(GetType(), "alert", "alert('Email sent.');", true);

Hope it helps...!