Messages stick in Local/Outbox folder

We just moved from WIn7 (using eMclient there) to Win8.1 on an MS Surface Pro 3. Have downloaded and installed the latest updated eMclient. New messages being  ‘sent’  go immediately to the Local/Outbox folder and sit there with a red icon on the folder that shows the number of unsent messages sitting in the folder.
Have deleted the MSN account and re-added the MSN account. Incoming messages seem to be working without issue, but any sent messages get stuck in the Local/outbox folder. When I attempt to go to the diagnosis/test tab for the account, there’s nothing on the tab to let me test my settings. I am using the automated eMclient configuration and have not attempted to specify any servers or whatever manually.
… puzzled

Hello MSN/Live and accounts (hosted with Microsoft) are using an AirSync protocol to synchronise your items with the server, if you’re having any issues while sending, please check the Operations window for errors or the Log in Operations for more detailed information about the sync process.

What version of eM Client are you currently using on your computer, can you please check the exact release number in Help > About? Are you using any security software on your computer, that may have disabled the application ability to connect to your mail server?