We have a user who's inbox disappeared last Friday afternoon. She sent an email, left her desk, and when she came back all of the emails in her inbox were gone. They were not in the Deleted Items folder, and we could not find them using Recover Deleted Items (she didn't delete them).
All of her emails that are in subfolders of the inbox are still there, and any emails she's received since then are still in the inbox. Sent emails are there as well. The emails are also not visible from the online portal.
When we use the Send/Receive function, we get the error: 0x80190194. I have recreated the profile on another computer and did not get that error, but the emails do not show up there either.
We currently use Office 365 E2 plan for nonprofits. The user also got a smart phone last week and we set that up, and hadn't been experiencing any issues with it. The computer is updated and doesn't have any viruses or malware.