Sending mail using gmail in .net

vb.net
Import namespace " System.Net.Mail".And add following coding on button click

Dim m As MailMessage =  New MailMessage() 
  m.To.Add("Email id of receiver")
  m.From = New MailAddress("Add your email it here")
  m.Subject = "Subject line of your mail is kept here"

  String Body = "Add you mail body here" 
   m.Body = Body
 
  mail.IsBodyHtml = True
  Dim smtp As SmtpClient =  New SmtpClient() 
  smtp.Host = "smtp.gmail.com" 
  smtp.Credentials = New System.Net.NetworkCredential
       ("your gmail id","password of gmail")
  smtp.EnableSsl = True
  smtp.Send(mail)

C# 

MailMessage mail = new MailMessage();
mail.From = new System.Net.Mail.MailAddress("your email");
SmtpClient smtp = new SmtpClient();
smtp.Port = 587;   
smtp.EnableSsl = true;
smtp.DeliveryMethod = SmtpDeliveryMethod.Network; 
smtp.UseDefaultCredentials = false; 
smtp.Credentials = new NetworkCredential("your emailid","password_here");
smtp.Host = "smtp.gmail.com";           

mail.To.Add(new MailAddress("receiver email"));
mail.IsBodyHtml = true;
string subject = "Test Mail";
mail.Body = subject;
smtp.Send(mail);

You can also add email sending credentials in web.config file as and 

just write following code

<system.net> 

    <mailSettings>

      <smtp from="sender@yourdomai.com">

        <network host="smtpserver1" port="25" userName="username" password="secret" defaultCredentials="true" />

      </smtp>

    </mailSettings>

  </system.net>

MailMessage message = new MailMessage();

message.From = new MailAddress("your email address");

message.To.Add(new MailAddress("receivers email address"));

message.CC.Add(new MailAddress("any email id as cc"));

message.Subject = "Place subject of mail here";

message.Body = "enter your message here";

SmtpClient client = new SmtpClient();

client.Send(message);