Asp.Net Identity 2.0 - 如何使用SmtpClient实现IIdentityMessageService来执行异步SMTP？

Question

I've implemented a simple EmailService for Asp.Net Identity 2.0 (via the IIdentityMessageService interface.

    public class EmailService : IIdentityMessageService
{
    public Task SendAsync(IdentityMessage message)
    {
        // convert IdentityMessage to a MailMessage
        var email = 
           new MailMessage(new MailAddress("noreply@mydomain.com", "(do not reply)"), 
           new MailAddress(message.Destination))
        {
            Subject = message.Subject,
            Body = message.Body,
            IsBodyHtml = true
        };

        using (var client = new SmtpClient()) // SmtpClient configuration comes from config file
        {
            return client.SendMailAsync(email);
        }
    }
}

To send an email, I go through UserManager:

await _userManager.SendEmailAsync(user.Id, "Confirm your account","Please confirm your account by clicking this link: <a href=\\"" + callbackUrl + "\\">link</a>");

The problem is that I get a System.Threading.Tasks.TaskCanceledException when I call SendEmailAsync() and it's not clear why.

If I send email synchronously ( client.Send(email) ), everything works fine.

So my questions are:

• How do I prevent the TaskCanceledException from getting thrown? and (assuming I can overcome this error),

• How should I go about communicating errors during email sending back to the client (ie, "no such user here" type responses from the SmtpClient?

Answer 1

Your problem is that SmtpClient is disposed before the email is sent.

Two ways:

• Await the SendMailAsync result

   using (var client = new SmtpClient()) { await client.SendMailAsync(email); } 

• Register the SendCompleted event and dispose the SmtpClient only after the message is sent

   var client = new SmtpClient(); client.SendCompleted += (s, e) => { client.Dispose(); }; return client.SendMailAsync(message); 

Answer 2

You must put async on method.

    public async Task SendAsync(IdentityMessage message)
    {
        using (SmtpClient client = new SmtpClient())
        {
                using (var mailMessage = new MailMessage("your@email.com", message.Destination, message.Subject, message.Body))
                {
                    await client.SendMailAsync(mailMessage);
                }
            }
        }
    }