Hi Twofourwheels,
Since this issue has multiple potential root causes, to help you troubleshoot it, I would like to confirm the following information:
1. Was everything working previously?
2. If you send an email via Outlook Web App (OWA), can you see the email on Outlook or iPad?
3. Does this issue occur to other users in your tenant?
4. Which kind of connection types are you using? POP, IMAP or Outlook Anywhere?
Thanks,
Jerry Cen