Current State:
If the user gets a “Another meetings user is using this URL. Please choose another URL.” message when trying to save a certain namespace, that means that namespace is taken by another user in any portal across HubSpot, not just in their portal. You cannot use this, unless you are the same person in that or another portal for some reason and are closing down a dupe portal/switching user emails, etc.
Even if the user is using a custom domain since we reserve the namespace on our domains too (e.g. meetings.hubspot.com), not just their custom domain, the namespace still has to be unique across all portals.
Desired State: If you’re using a custom domain, such as meetings.mycompany.com, you should not be limited by namespaces at the scope of the entirety of HubSpot.