In this article I will explain with an example, how to send email using JavaScript in ASP.Net with C# and VB.Net.
The Email will be sent by calling a Web Method using AJAX and XmlHttpRequest (XHR) in ASP.Net.
HTML Markup
The HTML Markup consists of three TextBoxes for Recipient Email address, Subject, Body and a Button to send the email.
The Button has been assigned with an OnClientClick event handler which makes call to a JavaScript function.
<table border="0" cellpadding="0" cellspacing="0">
        <td><asp:TextBox ID="txtTo" runat="server" /></td>
        <td><asp:TextBox ID="txtSubject" runat="server" /></td>
        <td valign ="top">Body:</td>
        <td><asp:TextBox ID="txtBody" runat="server" TextMode="MultiLine" Height="150" Width="200" /></td>
        <td><asp:Button ID="btnSend" Text="Send" runat="server" OnClientClick="return SendEmail()" /></td>
Mail Server Settings in Web.Config file
Following are the Mail Server settings in the Web.Config file.
        <smtp deliveryMethod="Network" from="">
                defaultCredentials="true" />
MailMessage Class Properties
Following are the required properties of the MailMessage class.
From – Sender’s email address.
To – Recipient(s) Email Address.
CC – Carbon Copies. (If any)
BCC – Blind Carbon Copies. (If any)
Subject – Subject of the Email.
Body – Body of the Email.
IsBodyHtml – Specify whether body contains text or HTML mark up.
Attachments – Attachments. (If any)
ReplyTo – ReplyTo Email address.
SMTP Class Properties
Following are the properties of the SMTP class.
Host – SMTP Server URL. (Gmail:
EnableSsl – Specify whether your host accepts SSL Connections. (Gmail: True)
UseDefaultCredentials – Set to True in order to allow authentication based on the Credentials of the Account used to send emails.
Credentials – Valid login credentials for the SMTP server. (Gmail: email address and password)
Port – Port Number of the SMTP server. (Gmail: 587)
You will need to import the following namespaces.
using System.Net;
using System.Net.Mail;
using System.Web.Services;
using System.Configuration;
using System.Net.Configuration;
Imports System.Net
Imports System.Net.Mail
Imports System.Web.Services
Imports System.Configuration
Imports System.Net.Configuration
Server Side Web Methods for sending Email
The following Web Method SendEmail accepts email address (toEmail), Subject and Body parameters and returns the String message.
Note: The method is declared as static (C#) and Shared (VB.Net) and also it is declared as WebMethod unless you do this you won’t be able to call the methods.
The Sender email address (from) is fetched from the SmtpSection of the Web.Config file.
All these values are set into an object of the MailMessage class.
Finally, object of the SmtpClient class is created and the settings of the Mail Server such has Host, Port, DefaultCredentials, EnableSsl, Username and Password are fetched from the mailSettings section of the Web.Config file and attached to the SmtpClient class object.
Finally, a string message is returned which will be later displayed using JavaScript Alert Message Box.
public static string SendEmail(string toEmail, string subject, string body)
    SmtpSection smtpSection = (SmtpSection)ConfigurationManager.GetSection("");
    using (MailMessage mm = new MailMessage(smtpSection.From, toEmail))
        mm.Subject = subject;
        mm.Body = body;
        mm.IsBodyHtml = false;
        using (SmtpClient smtp = new SmtpClient())
            smtp.Host = smtpSection.Network.Host;
            smtp.EnableSsl = smtpSection.Network.EnableSsl;
            NetworkCredential networkCred = new NetworkCredential(smtpSection.Network.UserName, smtpSection.Network.Password);
            smtp.UseDefaultCredentials = smtpSection.Network.DefaultCredentials;
            smtp.Credentials = networkCred;
            smtp.Port = smtpSection.Network.Port;
    return "Email sent.";
Public Shared Function SendEmail(ByVal toEmail As String, ByVal subject As String, ByVal body As String) As String
    Dim smtpSection As SmtpSection = CType(ConfigurationManager.GetSection(""), SmtpSection)
    Using mm As MailMessage = New MailMessage(smtpSection.From, toEmail)
        mm.Subject = subject
        mm.Body = body
        mm.IsBodyHtml = False
        Using smtp As SmtpClient = New SmtpClient()
            smtp.Host = smtpSection.Network.Host
            smtp.EnableSsl = smtpSection.Network.EnableSsl
            Dim networkCred As NetworkCredential = New NetworkCredential(smtpSection.Network.UserName, smtpSection.Network.Password)
            smtp.UseDefaultCredentials = smtpSection.Network.DefaultCredentials
            smtp.Credentials = networkCred
            smtp.Port = smtpSection.Network.Port
        End Using
    End Using
    Return "Email sent."
End Function
JavaScript XmlHttpRequest (XHR) function to send email in ASP.Net
The SendEmail JavaScript function is called when the Send Button is clicked.
Inside this function the ToEmail, Subject and Body values are fetched from the TextBoxes and an AJAX call is made using JavaScript XmlHttpRequest (XHR) function to the server and are passed as parameters to the Web Method SendEmail.
Note: The ID of the ASP.Net controls, tend to change when Master Pages or UserControls are used and hence the ClientID property is used to fetch the IDs of the controls. For more details, please refer ASP.Net: JavaScript document.getElementById returns NULL when using Master Page.
The value returned from the Web Method is fetched inside the onreadystatechange event handler of the JavaScript XmlHttpRequest (XHR) function and displayed using JavaScript Alert Message Box.
<script type="text/javascript">
    function SendEmail() {
        var toEmail = document.getElementById("<%=txtTo.ClientID%>").value;
        var subject = document.getElementById("<%=txtSubject.ClientID%>").value;
        var body = document.getElementById("<%=txtBody.ClientID%>").value;
        var request;
        if (window.XMLHttpRequest) {
            //New browsers.
            request = new XMLHttpRequest();
        else if (window.ActiveXObject) {
            //Old IE Browsers.
            request = new ActiveXObject("Microsoft.XMLHTTP");
        if (request != null) {
            var url = "Default.aspx/SendEmail";
  "POST", url, false);
            var params = "{ toEmail: '" + toEmail + "', subject: '" + subject + "', body: '" + body + "' }";
            request.setRequestHeader("Content-Type", "application/json");
            request.onreadystatechange = function () {
                if (request.readyState == 4 && request.status == 200) {
        return false;
Errors while sending Email using Gmail
The following error occurs when you try to send email using Gmail credentials in your ASP.Net application.
The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn more at
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Net.Mail.SmtpException: The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn more at
Email Form
Send email using JavaScript in ASP.Net
Received Email
Send email using JavaScript in ASP.Net
Browser Compatibility

The above code has been tested in the following browsers.
Internet Explorer  FireFox  Chrome  Safari  Opera 

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