C# Send Email With MailKit

mailkit_example.cs

namespace ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            var message = new MimeMessage();
            var bodyBuilder = new BodyBuilder();
            
            // from
            message.From.Add(new MailboxAddress("from_name", "from_email@example.com"));
            // to
            message.To.Add(new MailboxAddress("to_name", "to_email@example.com"));
            // reply to
            message.ReplyTo.Add(new MailboxAddress("reply_name", "reply_email@example.com"));

            message.Subject = "subject";
            bodyBuilder.HtmlBody = "html body";
            message.Body = bodyBuilder.ToMessageBody();

            var client = new SmtpClient();

            client.ServerCertificateValidationCallback = (s, c, h, e) => true;
            client.Connect("MAIL_SERVER", 465, SecureSocketOptions.SslOnConnect);
            client.Authenticate("USERNAME", "PASSWORD");
            client.Send(message);
            client.Disconnect(true);
        }
    }
}

@vmakwana you can use non-SSL by set only host parameter like this client.Connect("sc.mail.com");

Update 2019 !! :)