Sometimes it is possible to put Outlook into offline mode inadvertently.
You can tell that Outlook is Working Offline by the following message in the bottom right corner of Outlook:
You can fix this by going to the Send / Receive tab:
and deselecting the Work Offline option:
Was this article helpful?
That’s Great!
Thank you for your feedback
Sorry! We couldn't be helpful
Thank you for your feedback
Feedback sent
We appreciate your effort and will try to fix the article