title: Outlook slow connection and "A stable connection to the server could not be established." with MailCore2
body: <p>Im trying to fetch all mails headers from outlook, I successfully login to the account and calls like [session fetchAllFoldersOperation] and work without problems even fetching mails.</p>
  
  <p>Im requesting all the headers in batches of 50 at the time.
  i'm receiving batch messages very slow and some of the request are lost. 
  I receive "A stable connection to the server could not be established. error"
  This is only happening with outlook, i have no problems with gmail or yahoo.</p>
  
  <p>this is my session configuration.</p>
  
  <pre><code>self.username = username;
  self.password = password;
  self.hostname = ^ NSString *(SCMMailProvider provider) {
      if (provider == SCMServiceProviderGmail) {
          return @"imap.gmail.com";
      } else if (provider == SCMServiceProviderHotmail) {
          return @"imap-mail.outlook.com";
      } else if (provider == SCMServiceProvideriCloud) {
          return @"imap.mail.me.com";
      } else if (provider == SCMServiceProviderYahoo) {
          return @"imap.mail.yahoo.com";
      }
  
      return nil;
  }(provider);
  
  if (provider == SCMServiceProvideriCloud || provider == SCMServiceProviderOther) {
      self.mailsFolder = kSCMMailFolderInbox;
      [self setAuthType:MCOAuthTypeSASLNone];
  } else {
      [self setOAuth2Token:password];
      [self setUsername:username];
      if (provider == SCMServiceProviderHotmail) {
          [self setAuthType:MCOAuthTypeXOAuth2Outlook];
          self.mailsFolder = kSCMMailFolderInbox;
      } else if (provider == SCMServiceProviderGmail) {
          [self setAuthType:MCOAuthTypeXOAuth2];
          self.mailsFolder = kSCMGmailAllMessagesFolder;
      }
  }
  
  MCOIMAPFetchMessagesOperation *fetchOp = [self fetchMessagesByNumberOperationWithFolder:self.mailsFolder
                                                                              requestKind:MCOIMAPMessagesRequestKindStructure | MCOIMAPMessagesRequestKindHeaders
                                                                                  numbers:uidSet];
  [fetchOp start:^(NSError *messageFetchingError, NSArray *msgs, MCOIndexSet *vanished) {
  }
  </code></pre>