using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Net.Mail;

public partial class Email : BasePage
{
    protected void Page_Load(object sender, EventArgs e)
    {
      MailMessage myMessage = new MailMessage();
      myMessage.Subject = "Test message";
      myMessage.Body = "hello world,from planet wrox";
      myMessage.From = new MailAddress("myemailid", "my name");
      myMessage.To.Add(new MailAddress("receiver's emailid", "receiver's name"));
     
      SmtpClient mySmtpClient = new SmtpClient();
      mySmtpClient.Send(myMessage);
      mySmtpClient.EnableSsl = true;

    }
}

 <system.net>
    <mailSettings>
      <smtp deliveryMethod="Network" from="my emailid">
        <network host="smtp.myprovider.com"/>

      </smtp>
    </mailSettings>
  </system.net> 
  
</configuration>

<div id="contactForm" class="contactForm" tabindex="0">

    <div id="contactImage" title="Contact Us!"></div>

    <h2 title="Contact the Best Public Domain Library on Earth">Have a Question? Leave a comment!</h2>

    <h4 title="Make the Best Public Domain Library on Earth better!">Add an update, make a suggestion, or report an error.</h4>

    <fieldset>
    <!-- NOTE: Label tags use the for attribute to connect with the id of a particular control. -->

        <legend>Contact Us!</legend>

        <ol>
            <li>
                <label for="ctl00_ctl00_placeholderForContactForm_component_ContactForm_questionsAndCommentsTextarea">Questions and Comments</label>
                <asp:textbox runat="server" id="questionsAndCommentsTextarea" textmode="multiLine" />
            </li>
            <li>
                <label for="ctl00_ctl00_placeholderForContactForm_component_ContactForm_emailTextbox">Email (optional)</label>
                <asp:textbox runat="server" id="emailTextbox" />
            </li>
            <li>
                <asp:button runat="server" id="button_EmailQuestionsAndComments" text="Email Us!" OnClick="EmailQuestionsAndComments" />
                <asp:Label runat="server" ID="contactFormMessage"></asp:Label>
            </li>
        </ol>

    </fieldset>

</div>

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Net;
using System.Net.Mail;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class ContactForm : System.Web.UI.UserControl
{

    protected void Page_Load(object sender, EventArgs e)
    {
        //testing to see if the page works
        this.contactFormMessage.Text = "Ask Us!";
    }
    
    protected void EmailQuestionsAndComments(object sender, EventArgs e)
    {
        // Declaring necessary mail variables
        MailMessage contactFormEmail = new MailMessage(); // the email (technically mail message)
        NetworkCredential emailAccountCredentials = new NetworkCredential("systemEmailUserName", "systemEmailPassword"); // the authentication credentials
        SmtpClient smtpAccount = new SmtpClient("mail.myDomain.com", 25); // the SMTP account and port#
        Uri urlOfVisitedPage = Request.Url; // the URL of the current webpage (this subroutine will run on every page of the website, so we don't know if we don't go grab it)

        // the email configuration information: sender, recipients, subject
        contactFormEmail.From = new MailAddress("Admin <[email protected]>");
        contactFormEmail.To.Add(new MailAddress("[email protected]")); // Copy this line to send to multiple email addresses
        // contactFormEmail.To.Add(new MailAddress("[email protected]"));
        contactFormEmail.Subject = "I have a question or comment.";
        contactFormEmail.IsBodyHtml = true;

        // the body of the email
        contactFormEmail.Body = "<p>Hi!</p> <p>You have a message from an Earth Chronicle visitor. They responded to <a href='" + urlOfVisitedPage.AbsoluteUri + "'>" + urlOfVisitedPage.AbsoluteUri + "</a></p>";
        contactFormEmail.Body += "<p>Their email is: " + this.emailTextbox.Text + "</p>";
        contactFormEmail.Body += "<p>They write:" + this.questionsAndCommentsTextarea.Text + "</p>";
        contactFormEmail.Body += "<p>TTFN,<br />the Server</p>";

        // SMTP configuration information and use the Send method
        smtpAccount.UseDefaultCredentials = false;
        smtpAccount.Credentials = emailAccountCredentials;
        smtpAccount.Send(contactFormEmail);

        // notify the visitor that the procedure has successfully completed
        this.contactFormMessage.Text = "Sent.";
    }
}