C# - Put Email Messages In A Queue When SMTP Server Is Down?

I have a big problem with my SMTP server for sending emails. It's down often. At this point I am using this code:

MailMessage mailMsg = new MailMessage();
mailMsg.From = new MailAddress("fromMail@example.com");
mailMsg.To.Add("toMail@example.com");
mailMsg.Subject = "...";
mailMsg.IsBodyHtml = true;
mailMsg.BodyEncoding = Encoding.UTF8;
mailMsg.Body = "Mail";
mailMsg.Priority = MailPriority.High;
SmtpClient client = new SmtpClient();
client.Credentials = new NetworkCredential("account@gmail.com", "password");
client.Port = 456;
client.Host = "smtp.gmail.com";
client.EnableSsl = true;
client.Send(mailMsg);

But, when my SMTP server is down I want to put all the emails in a queue and when it recovers I want to send them one a time. Is there any way how to do this programatically in C#?