Sending, receiving, and organizing email in Outlook.com
Thank you for the additional details. Since the messages are missing in both Outlook for Windows and Outlook Mobile, this is unlikely to be an issue with only one app or device. The timing of the email claiming that your account would be closed is also concerning, although the timing alone does not confirm that the message caused the problem.
Please do not select any links or attachments in that message. Instead, open your Microsoft account directly in a browser and review Security > Recent activity for any sign-ins, devices, or security changes you do not recognize. I also recommend changing your password to a new, unique one, enabling two-step verification, and using the option to sign out everywhere. Missing messages and unauthorized forwarding or deletion rules can be signs that an account was accessed by someone else. You can report the suspicious message in Outlook by selecting Report > Report phishing.
Because the messages are missing across both devices and the previous recovery steps did not help, please contact Outlook.com Support through Help in Outlook.com and request a mailbox-level review. Include the approximate disappearance time, October 21 at 10:00 AM ET, and mention the suspicious email received on October 20.
Please note that this is a user-to-user support forum. Moderators, contributors including external Microsoft employees cannot directly intervene in Microsoft product features or access back-end systems. Our role is limited to providing technical guidance on reported issues, requests, or ideas only.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.