Outlook Message Manager (profile_name) (KEY hex_number) email items in an Exchange Online mailbox
Original KB number: 2937277
When you use Microsoft Outlook to connect to a Microsoft 365 email account, one or more messages that have the following Subject line may appear in your Inbox:
Outlook Message Manager (profile_name) (KEY: hex_number)
The profile_name placeholder represents the name of your Outlook messaging profile, and hex_number represents a hexadecimal string that consists of a combination of numbers and letters from A-F.
This issue occurs only when your Outlook messaging profile has the Exchange email account set up to use Online mode.
You can safely move these messages to the Deleted Items folder.
Microsoft is researching this problem and will post more information in this article when the information becomes available.
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