Sometimes Microsoft Outlook will go into offline mode.
This means you will not be able to send or receive any emails.
Follow these steps to turn off Offline Mode.
1. Click the Send/Receive tab in the top ribbon.
2. On the far right of the bar, you will see the work offline high lighted. Click it to turn it off.
3. Your inbox should start connecting again. Take note it could take a few minutes to sync and update.