Booking Microsoft resource calendars with Free/Busy

When creating an event with a Calendar in Free/Busy access mode, Cronofy doesn’t directly put the event into the calendar, but instead invites the calendar to an event via email.

In this scenario, Cronofy acts as the calendar provider and handles sending the event invitations and updates via email, with the ICS file attached.

You can set up your resource calendar to accept Cronofy events automatically, removing the need for an admin to go in and manually approve a booking.

Configuring the resource to auto-accept invites #

For these emailed invites to be accepted automatically, the calendar admin needs to configure the resource mailbox. By default a Microsoft resource will not accept invites from senders outside its own tenant, so Cronofy’s invites will be ignored without this step.

This is done with the Set-CalendarProcessing cmdlet in PowerShell:

Connect-ExchangeOnline

Set-CalendarProcessing -Identity "room@yourdomain.com" `
  -AutomateProcessing AutoAccept `
  -AllowConflicts $false `
  -ProcessExternalMeetingMessages $true `
  -AllBookInPolicy $true `
  -AllRequestInPolicy $false `
  -AllRequestOutOfPolicy $false

The key parameters are:

• -AutomateProcessing AutoAccept — invites are accepted automatically, removing the need for a delegate to accept them.
• -ProcessExternalMeetingMessages $true — the critical one. It allows the resource to accept invites from senders outside the tenant, which Cronofy’s invites are. This is $false by default.
• -AllBookInPolicy $true and -AllRequestInPolicy $false — everyone is treated as a “book in policy” user, so requests are accepted outright rather than forwarded to a delegate.
• -AllowConflicts — set $false to reject double-bookings, or $true to accept every invite regardless of conflicts.

Result #

With this configuration in place, inviting an Office 365 resource calendar’s email address as an attendee on a Free/Busy event will be added to the calendar and the resource will auto-accept the booking.