Classic Outlook users are seeing stale entries in search results after moving or modifying mailbox items. Clicking a moved message triggers an error, and changes to categories or read/unread status may not be reflected. The problem is specific to Server Assisted Search for mailboxes running in online mode.
Microsoft has acknowledged the bug and, for now, the workaround is a registry change that disables server-assisted searching, forcing Classic Outlook to use Windows Desktop Search. The company says a fix has been escalated as a hotfix to the Outlook team, but no ETA has been given.
The bug adds to a list of recent issues in the classic client, which Microsoft is steering users away from. The opt-out phase begins in 2027, when affected enterprise users will be moved to New Outlook by default unless administrators block it, and a later cutover will remove the option to switch back. Microsoft has also added Copilot to Classic Outlook and fixed a voicemail attachment issue in build 16.0.20430.2000 and later, but the search bug remains unresolved.