title: Error when I'm using MailCore2 in Swift 2
body: <p>I'm using the MailCore2 at Swift in my iOS application to send message to email in the background without open built-in mail application, But when I'm running app on my device ( real device ) I have this problem:</p>
  
  <p>My complete code for send button:</p>
  
  <pre><code>@IBAction func sendButton(sender: AnyObject) {
  
      var smtpSession = MCOSMTPSession()
      smtpSession.hostname = "smtp.gmail.com"
      smtpSession.username = "from-email"
      smtpSession.password = "password"
      smtpSession.port = 465
      smtpSession.authType = MCOAuthType.SASLPlain
      smtpSession.connectionType = MCOConnectionType.TLS
      smtpSession.connectionLogger = {(connectionID, type, data) in
          if data != nil {
              if let string = NSString(data: data, encoding: NSUTF8StringEncoding){
                  NSLog("Connectionlogger: \(string)")
              }
          }
      }
  
      var builder = MCOMessageBuilder()
      builder.header.to = [MCOAddress(displayName: "AAA", mailbox: "to-email")]
      builder.header.from = MCOAddress(displayName: "RRR", mailbox: "from-email")
      builder.header.subject = messageTitleTextField.text
      var message = messageTextView.text
      builder.htmlBody = message
  
      let rfc822Data = builder.data()
      let sendOperation = smtpSession.sendOperationWithData(rfc822Data)
      sendOperation.start { (error) -&gt; Void in
          if (error != nil) {
              NSLog("Error sending email: \(error)")
          } else {
              NSLog("Sent successfully, Thanks!")
          }
      }
  }
  </code></pre>
  
  <p>Error:</p>
  
  <pre><code> Optional(Error Domain=MCOErrorDomain Code=5 "Unable to authenticate with the current session's credentials." UserInfo={NSLocalizedDescription=Unable to authenticate with the current session's credentials.})
  </code></pre>