iOS + SmtpClient + PickupDirectoryLocation + attachment = über slow?

Hello, everybody.

I tried to send an Email with a 10mb+ movie (.mov) attachment using the somewhat usual approach with MailMessage and SmtpClient classes form the System.Net.Mail namespace of Mono. It was taking unforgivably long (although was working) so I blamed on the server or whatnot and I decided to try an alternative.

I specified the delivery method to be a pickup directory which practically means that instead of sending anything the SMTP client would just create a local file.

 _smtpClient = new SmtpClient(_smtpClientHost, _smtpClientPort);
 
 _smtpClient.DeliveryMethod = SmtpDeliveryMethod.SpecifiedPickupDirectory;
 _smtpClient.PickupDirectoryLocation = Application.persistentDataPath;
 
 _smtpClient.Timeout = (int)(_smtpClientTimeout * 1000.0F); // Seconds to milliseconds
 _smtpClient.UseDefaultCredentials = false;
 _smtpClient.Credentials = (ICredentialsByHost)new NetworkCredential(_smtpClientCredentialsUserName, _smtpClientCredentialsPassword);
 _smtpClient.EnableSsl = _smtpClientEnableSsl;
 
 ServicePointManager.ServerCertificateValidationCallback = 
                 (object s, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) => { return true; };

I made sure nothing stands on the way and simply put the iPad to Flight Mode. To my surprise it still took about 30 (THIRTY) minutes to simply create a 10mb heavy .eml file locally.

Have you experienced anything similar and would you have a solution to this? Or is this the nature of SMTP and I should just say goodbye to it?

PS: Just sending the same 10mb .mov file with the native Mail client takes seconds.