Disablesyncsliderforsharedmailbox _top_ Jun 2026

GET https://graph.microsoft.com/v1.0/me/mailFolders/inbox/messages

There is nothing more frustrating for a helpdesk team than logging into a Shared Mailbox only to find that Outlook has arbitrarily decided to only sync the last 12 months of emails, hiding critical older correspondence. The default behavior (Sync Slider) makes sense for personal mailboxes to save disk space, but it is counter-productive for Shared Mailboxes which often act as archives.

This setting should be the standard default for any organization relying on shared mailboxes for team collaboration. It eliminates the friction of limited email history and restores the utility of shared resources.

| Problem | Solution | |---------|----------| | Setting doesn’t work | Ensure Outlook is closed when editing registry. Confirm path matches your Office version. | | Outlook still only shows 12 months | Right-click the folder > > Clear Offline Items > restart Outlook to force a full resync. | | Mac version not respecting command | Use Outlook’s account settings to set "Download all messages" instead. | | OST file too large | Revert setting to 0 , then run Mailbox Cleanup tools. |