ErrorItemNotFound — Specified object was not found

The requested item (email, event, etc.) was not found via Graph. It may have been moved or deleted. Verify the item ID and the mailbox you are querying. If you obtained the ID earlier, try refreshing your data using Riposte (for example, fetch the latest messages list via /accounts/{accountId}/messages). If the item truly doesn't exist, handle this gracefully (e.g., inform the user or skip the item).