Using Graph API requires registration in Azure AD and appropriate permissions.
By default, the "Sync Slider" (often defaulting to 3 months or 1 year) applies to all mail objects during migration or profile creation. While this saves bandwidth and storage for individual user mailboxes, it is detrimental for functional mailboxes (e.g., info@ , support@ , or Archive mailboxes). These mailboxes often require a full history of correspondence to be immediately accessible to team members. Previously, admins had to manually adjust the slider via OWA or Outlook after the fact, leading to user downtime and sync delays. disablesyncsliderforsharedmailbox
The registry value is a specialized configuration used in Microsoft Outlook (2016 and later) to control how much email is stored locally for shared mailboxes. By default, Outlook limits the synchronization of shared mailboxes to a specific timeframe—typically the last 12 months—to manage local storage and improve performance. Purpose and Functionality Using Graph API requires registration in Azure AD