Our resource booking calendar synchronization is failing when we try to use shared mailboxes for equipment resources. We configured shared mailboxes in Exchange for our conference rooms and equipment resources, but the calendar sync through the Exchange connector keeps failing with authentication errors.
The synchronization works perfectly for individual user mailboxes, but shared mailboxes fail during the sync process. We need the shared mailbox approach because multiple project managers need to book these resources, and individual mailboxes create ownership issues. The Exchange connector setup appears correct, and we’ve verified the shared mailbox permissions in Office 365.
This is disrupting our project scheduling workflow because resource availability isn’t accurately reflected in D365. Project managers are double-booking resources because the calendar sync doesn’t pull the actual bookings from the shared mailboxes. Has anyone successfully configured calendar sync with shared mailboxes for resource management?
The “Access denied” error usually means the Azure AD app registration doesn’t have the right API permissions. You need to grant application permissions, not delegated permissions. In Azure AD, go to your D365 app registration, then API permissions, and add Microsoft Graph application permissions for Calendars.ReadWrite and Mail.Send. After adding these, make sure to grant admin consent. The delegated permissions work for user mailboxes but fail for shared mailboxes because there’s no interactive user to delegate to.
Don’t forget about the resource booking sync configuration in D365 itself. Even with correct Exchange permissions, the resource records need to be properly configured for calendar sync. In Project management and accounting > Setup > Resources, verify that each resource is linked to the correct shared mailbox email address and that the “Enable calendar synchronization” checkbox is marked. The sync won’t work if the resource record doesn’t have the email address matching the shared mailbox.
Shared mailboxes require different authentication settings in the Exchange connector. Regular user mailboxes use OAuth with user credentials, but shared mailboxes need application-level authentication. Check your Exchange connector configuration in System administration > Setup > Exchange connector parameters. You might need to switch from user-based OAuth to app-based authentication with proper permissions granted in Azure AD for the shared mailboxes.