Add Microsoft Graph API support to identify and manage Shared Mailboxes

Is your feature request related to a problem? Please describe the problem.

Currently, Microsoft Graph does not provide a way to identify Shared Mailboxes in Exchange Online.
When querying /users, the userType property only returns Member, Guest, or Federated, and does not indicate whether the account is a shared mailbox.

This creates a compliance and automation gap:

Administrators cannot programmatically verify which accounts are shared mailboxes.

Security audits (e.g., checking that sign-in is blocked for shared mailboxes) require Exchange Online PowerShell (Get-Mailbox -RecipientTypeDetails SharedMailbox), which prevents full automation via Graph

Describe the solution you'd like.

Microsoft Graph should expose Shared Mailbox details directly. This would allow admins to retrieve shared mailbox details (e.g., mailbox type, sign-in status, licensing, members) directly via Graph.

Additional context?

No response

Start by reviewing how the Go SDK models /users and exposes the userType property, then compare that surface with the requested shared-mailbox details. The issue also references Get-Mailbox -RecipientTypeDetails SharedMailbox as the current workaround. Done would require a defined Microsoft Graph and SDK approach for identifying and managing shared mailboxes, including the requested mailbox metadata.