Speed up sending multiple emails through smtp server using System.Net.Mail
simply use multiple threads (multiple processes).
In C# you can do this with a Task.
new Task(delegate { smtpClient.send(myMessage); }).Start();Just wrap your send command in this object and it will be send Asynchronously.
Be careful if this is wrapped in a loop it will start a new process for each mail.
if you need to send large amounts of mails at the same time I suggest you use a ThreadPool. It lets you control how many concurent threads you'd like to have at the same time.