Send Asynchronous Mail With Attachment Using ASP.Net 4.5

Introduction

This article explains how to send an email with attachments using SmtpClient.SendAsync. My previous article explained sending Asynchronous Emails in ASP.NET 4.5 I will now explain how to implement send asynchronous mail with an attachment in ASP.NET 4.5.

Creating an Asynchronous Page

Create a new project using "File" -> "New" -> "Project..." then select web "ASP .Net Web Forms Application". Name it " SendMailAsyncAttachment ".



Next, create the code-behind as follows: The first step to building an asynchronous page is setting the Async attribute in the Page directive to true, as shown here:



<%@ Page Language="C#" Async="true" %>

Now, in the code behind file SendMailAttach.aspx use the following code.

SendMailAttach.aspx

<%@ Page Title="Sendmailasync with attachment" Async="true" Language="C#"
MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="SendMailAttach.aspx.cs"
Inherits="SendMailAsyncAttachment.SendMailAttach" %
<asp:Content ID="Content1" ContentPlaceHolderID="titleContent" runat="server">Sendmailasync with
attachment
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="head" runat="server">
    <script type="text/javascript">
        function validationCheck() {
            var summary = "";
            summary += isvalidName();
            summary += isvalidEmail();
            summary += isvalidSubject();
            summary += isvalidMessage();
            if (summary != "") {
                alert(summary);
                return false;
            }
            else {
                return true;
            }
        }
        function isvalidName() {
            var id;
            var temp = document.getElementById("<%=txtName.ClientID %>");
            id = temp.value;
            if (id == "") {
                return ("Please enter Name" + "\n");
            }
            else {
                return "";
           }
        }
        function isvalidEmail() {
            var id;
            var temp = document.getElementById("<%=txtEmail.ClientID %>");
             id = temp.value;
             var re = /\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*/;
             if (id == "") {
                 return ("Please Enter Email" + "\n");
             }
             else if (re.test(id)) {
                 return "";
             }

             else {
                 return ("Email should be in the form [email protected]" + "\n");
             }
         }
         function isvalidSubject() {
             var id;
             var temp = document.getElementById("<%=txtSubject.ClientID %>");
            id = temp.value;
            if (id == "") {
                return ("Please enter Subject" + "\n");
            }
            else {
                return "";
            }
        }
        function isvalidMessage() {
            var id;
            var temp = document.getElementById("<%=txtMessage.ClientID %>");
             id = temp.value;
             if (id == "") {
                 return ("Please enter Message" + "\n");
             }
             else {
                 return "";
             }
         }

    </script>
</asp:Content>
<asp:Content ID="Content3" ContentPlaceHolderID="MainContent" runat="server">
     <table style="width: 100%;">
        <tr>
            <td>Name:</td>
            <td>
                <asp:TextBox ID="txtName" runat="server" CssClass="txt"></asp:TextBox></td>
            <td> </td>
        </tr>
        <tr>
            <td>Email ID:</td>
            <td>
                <asp:TextBox ID="txtEmail" runat="server" CssClass="txt"></asp:TextBox></td>
            <td> </td>
        </tr>
        <tr>
            <td>Subject:</td>
            <td>
                <asp:TextBox ID="txtSubject" runat="server" CssClass="txt"></asp:TextBox></td>
            <td> </td>
        </tr>
         <tr>
             <td>Attach a file:</td>
             <td>
                 <asp:FileUpload ID="FileUpload1" runat="server" AllowMultiple="true" />
             </td>
             <td></td>
         </tr>
        <tr>
            <td>Message:</td>
            <td>
                <asp:TextBox ID="txtMessage" runat="server" Height="100px" Width="200px"
CssClass="textarea" TextMode="MultiLine"></asp:TextBox>
            </td>
            <td> </td>
        </tr>
        <tr>
            <td></td>
            <td>
                <asp:Button ID="btnSendMail" runat="server" Text="Send Mail" CssClass="button"
OnClick="btnSendMail_Click" /></td>
        </tr>
    </table>
</asp:Content>

Create a SmtpClient.SendCompleted Event and SmtpClient.SendAsyncCancel Method and attachment

Now, in the code behind file “SendMailAttach.aspx.cs “ use the following code.

SendMailAttach.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.IO;
using System.Net;
using System.Net.Mail;
using System.Net.Mime;
using System.Threading;
using System.ComponentModel;
using System.Text;
using System.Web.Util;

namespace SendMailAsyncAttachment
{
    public partial class SendMailAttach : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            Try
            {
                if (!Page.IsPostBack)
                {
                    btnSendMail.Attributes.Add("onclick", "javascript:return validationCheck()");
                }
            }
            catch (Exception ex)
            {
                ShowMessage(ex.Message);
            }
        }
        #region show message
        /// <summary>
        /// This function is used for show message.
        /// </summary>
        /// <param name="msg"></param>
        void ShowMessage(string msg)
        {
            ClientScript.RegisterStartupScript(Page.GetType(), "validation", "<script
language='javascript'>alert('" + msg + "');</script>");
        }
        #endregion
        #region SendAsyncCancel
        /// <summary>
        /// this code used to SmtpClient.SendAsyncCancel Method
        /// </summary>
        // static bool mailSent = false;
        void SendCompletedCallback(object sender, AsyncCompletedEventArgs e)
        {
            if (e.Cancelled)
            {
                ShowMessage("Send canceled.");
            }
            if (e.Error != null)
            {
                ShowMessage(e.Error.ToString());
            }
            else
            {
                ShowMessage("Email sent successfully");
            }
        }
        #endregion
        #region SendMailAsync
        /// <summary>
        /// this code used to SmtpClient.SendCompleted Event and attaching the file
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void btnSendMail_Click(object sender, EventArgs e)
        {
            Try
            {
                MailMessage message = new MailMessage();
                message.To.Add(txtEmail.Text.Trim());
                message.From = new MailAddress("[email protected]","Sendmailasync Test");
                message.Subject = txtSubject.Text.Trim();
                message.Body = txtMessage.Text.Trim();
                message.IsBodyHtml = true;
                if (FileUpload1.HasFile)
                {
                    message.Attachments.Add(new Attachment(FileUpload1.PostedFile.InputStream,
FileUpload1.FileName));
                }
                SmtpClient smtp = new SmtpClient();
                smtp.Host = "smtp.gmail.com";
                smtp.Credentials = new System.Net.NetworkCredential("[email protected]", "YouPassword");
                smtp.SendCompleted += new SendCompletedEventHandler(SendCompletedCallback);
                smtp.EnableSsl = true;
                smtp.SendMailAsync(message);
            }
            catch (Exception ex)
            {
                ShowMessage(ex.Message);
            }
            clear();
        }
        #endregion
        #region
        /// <summary>
        /// This Function is used TextBox Empty.
        /// </summary>
        void clear()
        {
            txtName.Text = string.Empty; txtEmail.Text = string.Empty; txtSubject.Text = string.Empty;
            txtMessage.Text = string.Empty;
            txtName.Focus();
        }
        #endregion
    }
}

Now run the page, it will look like this:



Now, show in the Message box “Email sent successfully”.



Now, see the following screen: SendMailAsync with Attachment.



I hope this article is useful. If you have any other questions then please provide your comments in the following.