Question

I read this on MSDN documentation, which seems to imply that I will still need to wait after calling the SendAsync method in my code, which is pasted below. Is this right? If it is, then I might as well just use the synchronous method of Send rather than SendAsync. My goal was to go to the next email message in my loop and send it without waiting for the previous one to be sent, which would allow me to handle the emailMessages collection more quickly as compared to using Send method. But it doesn’t seem true.

After calling SendAsync, you must wait for the e-mail transmission to complete before attempting to send another e-mail message using Send or SendAsync.

I am using C# and .Net framework 4.5. In my code, I am trying to send multiple emails from within a loop as in code below using SendAsync method.

List<EmailMessage> emailMessages = DAL.GetEmailsToBeSent();
SmtpClient client = new SmtpClient(); 

foreach(EmailMessage emailMessage in emailMessages)
{
  //create a message object from emailMessage object and then send it asynchronously
  client.SendAsync(message);
 //client.Send(message);
}

Answer 1

The advantage of the async method over the non-async alternative is that you don’t need to block the current thread. This is particularly helpful in UI environments where you don’t want to be blocking the UI thread, and also prevents the need for blocking a thread pool thread.

If you’re just going to do a blocking wait on the results, it has no advantage over the non-async alternative.