Step 2 — Room mailbox, then room list

A room needs two things to appear in discovery: it must be a room mailbox, and it must belong to a room list. Only the first has a user interface.

The mailbox (admin centre)

admin.microsoft.com → Show all → Resources → Rooms & equipment → Add resource. Resource type must be Room, not Equipment — equipment mailboxes never appear under microsoft.graph.room, whatever else is configured correctly.

Give it its own address, such as pod01@yourdomain.com. Do not reuse a person's mailbox: a user mailbox cannot be a room resource, needs a licence, and will never show up in /places no matter how it is shared.

The room list (PowerShell only)

There is no UI for this anywhere in the admin centre. The "room groups" shown there are a different object that /places does not read.

Connect-ExchangeOnline

New-DistributionGroup -Name "ZenSpace Pods" ` -PrimarySmtpAddress "zenspace-pods@yourdomain.com" ` -RoomList

Add-DistributionGroupMember ` -Identity "zenspace-pods@yourdomain.com" ` -Member "pod01@yourdomain.com"

The -RoomList switch is what separates this from an ordinary distribution group. Without it the group is created, members are added, everything reports success — and discovery still returns nothing.

One confusing detail while verifying: a room mailbox reports RecipientType: UserMailbox. That is correct and not a mistake. The field that identifies it is RecipientTypeDetails: RoomMailbox.