how to create mail service with C# code example

Example: c# application add mail service

var mailMessage = new MimeMessage();
mailMessage.From.Add(new MailboxAddress("from name", "from email"));
mailMessage.To.Add(new MailboxAddress("to name", "to email"));
mailMessage.Subject = "subject";
mailMessage.Body = new TextPart("plain")
{
    Text = "Hello"
};

using (var smtpClient = new SmtpClient())
{
    smtpClient.Connect("smtp.gmail.com", 587, true);
    smtpClient.Authenticate("user", "password");
    smtpClient.Send(mailMessage);
    smtpClient.Disconnect(true);
}