Blind Booking lets you connect a shared Exchange resource mailbox, the Virtual Room, to Planner. When people book meetings against that mailbox from Outlook, the meetings come into Planner as placeholders, even if they overlap in time. A coordinator then assigns the actual physical room to each one.
Use it when staff book a generic “meeting room” address from Outlook and you want a coordinator to decide which real room each booking gets, without Exchange rejecting overlapping requests.
There are three steps to set this up and use it:
Configure the Exchange room mailbox to accept overlapping bookings.
Configure the Virtual Room in Planner admin.
Book and assign rooms.
Step 1 — Configure the Exchange room mailbox to accept overlapping bookings
Why this is needed
A normal Exchange room mailbox automatically declines any request that clashes with a meeting it has already accepted. That is how it stops a single room being double-booked.
For a Virtual Room that behaviour is wrong. Many people will book the same shared address at overlapping times, and you want every one of those requests to come through so a coordinator can hand them out to real rooms. So the Virtual Room mailbox must be told to accept conflicting requests. Planner takes care of the real room conflicts later, when the coordinator assigns rooms.
Note: This change applies only to the dedicated Virtual Room mailbox. Leave your real meeting-room mailboxes as they are; they should keep rejecting conflicts so they are never double-booked.
How to configure it
Create (or pick) a dedicated Exchange resource mailbox to act as the Virtual Room. Then, using Exchange Online PowerShell, allow it to accept conflicts:
# Connect to Exchange Online
Connect-ExchangeOnline
# Allow overlapping bookings on the Virtual Room mailbox
Set-CalendarProcessing -Identity "[email protected]" `
-AutomateProcessing AutoAccept `
-AllowConflicts $true
What each setting does:
Setting | Value | Why |
|
| The mailbox automatically accepts requests instead of leaving them pending. |
|
| The required setting. Lets the mailbox accept meetings that overlap others, with no automatic decline. |
Check the result:
Get-CalendarProcessing -Identity "[email protected]" | Format-List AutomateProcessing, AllowConflicts
AllowConflicts must show True.
Only AllowConflicts is required. You don’t need to change AllowRecurringMeetings; it already defaults to True, so recurring meetings are accepted as-is.
Step 2 — Configure the Virtual Room in Planner admin
Open Planner Web Admin.
Go to Administration → Integrations → Calendar Synchronization.
Find the Virtual Room card.
In your tenant’s row:
Virtual Room Exchange Email — enter the mailbox address from Step 1 (for example
[email protected]).Active — tick the checkbox to enable it.
Click Update. You should see “Virtual Room updated successfully”.
Rules and common errors
The Virtual Room address must be a valid email and must be unique; it can’t be the same as something Planner already knows. Update is rejected if the address:
is not a valid email, or is too long;
matches an existing physical room;
matches a service / calendar-sync account;
matches another tenant’s Virtual Room;
matches an existing user.
You’ll also be blocked if calendar synchronization isn’t connected for the tenant.
To pause vs. remove it
Untick Active then Update → the address is kept but ignored (paused).
Clear the email then Update → the Virtual Room is removed.
Step 3 — Booking and assigning rooms
For the person booking (in Outlook)
Create a meeting in Outlook.
Add the Virtual Room mailbox (
[email protected]) as the room, the same way you’d add any room.Send the invite. It is accepted even if it overlaps other bookings, and no physical room is chosen yet.
For the coordinator (in Planner)
The meeting appears in Planner as a placeholder waiting for a room.
Open the Bookings page.
Filter by “Only Virtual meetings” to see the placeholders that still need a room.
Open a meeting and assign a physical room.
Save.
Once a room is assigned, the meeting becomes a normal booking and the organiser receives their confirmation. A Virtual Room placeholder must be given at least one real room before it can be saved.