Send Mail by gmail account in ASP.NET

You can integrate mail via gmail account but make sure that gmail settings allow less secure app. Click on Gmail settings & allow less secure app (gmail->Setttings->allow less secure app)

MailMessage mail = new MailMessage();
mail.From = new MailAddress("xyz@gmail.com");
mail.Sender = new MailAddress("xyz@gmail.com");
mail.To.Add("external@emailaddress");
mail.IsBodyHtml = true;
mail.Subject = "Email Sent";
mail.Body = "Body content from";
SmtpClient smtp = new SmtpClient("smtp.gmail.com", 587);
smtp.UseDefaultCredentials = false;
smtp.Credentials = new System.Net.NetworkCredential("xyz@gmail.com", "your_password");
smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
smtp.EnableSsl = true;
smtp.Timeout = 30000;
try
{
     smtp.Send(mail);
}
catch (SmtpException e)
{
    textBox1.Text= e.Message;
}