Send Asynchronous Email in ASP.Net 4.5

This article explains how to send asynchronous mail using a SmtpClient.SendCompleted Event and a SmtpClient.SendAsyncCancel Method in ASP.NET 4.5 for sending the specified message to an SMTP server for delivery as an asynchronous operation.

So, let's proceed with the following procedure:

Create an Asynchronous Page ASP.NET web page
Create a SmtpClient.SendCompleted Event and SmtpClient.SendAsyncCancel Method

Creating an Asynchronous Page

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

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

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

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

SendMail.aspx

<%@ Page Title="SendMailAsync|SendAsyncCancel" Async="true" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="SendMail.aspx.cs" Inherits="SendMailAsync.SendMail" %>
<asp:Content ID="Content1" ContentPlaceHolderID="titleContent" runat="server">
Send Email Asynchronously
</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>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

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

SendMail.aspx.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
//Using namespaces
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 SendMailAsync
{
public partial class SendMail : 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
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
protected void btnSendMail_Click(object sender, EventArgs e)
{
try
{
MailMessage message = new MailMessage();
message.From = new MailAddress("[email protected]");
message.To.Add(txtEmail.Text.Trim());
message.Subject = txtSubject.Text.Trim();
message.Body = "<b>Hi:</b> <br/><br>Name: " +
txtName.Text.Trim() + "<br/><br>Message: " +
txtMessage.Text.Trim() + "<br/><br>" ;
message.IsBodyHtml = true;
message.Priority = MailPriority.High;
SmtpClient smtp = new SmtpClient("smtp.gmail.com");
smtp.Port = 587;
smtp.Credentials = new 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”.

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

6 Comments

Join the conversation! Your thoughts help the community grow.

Aanchal Singh6y ago
How to implement this code in the class. this working fine for the single page. but when im implementing in the class getting error (BC30451: Name 'this' is not declared.). Please suggest
anand sutar11y ago
Uncomplit Source Code....resolved Properly System.net.Mail.SmtpClient doesn't contains the defination of SendMailAsync
anand sutar11y ago
Hello Sir, System.net.Mail.SmtpClient doesn't contains the defination of SendMailAsync
Raja Shekar12y ago
thank u
Raja Shekar12y ago
smtp.SendMailAsync(message); here am getting missing reference error please help me
- Sanjay Kumar12y ago
  <%@ Page Language="C#" Async="true" %>