Work top to bottom. Until every piece above it is in place, the invite option does not appear on the group. That reads like a missing feature rather than a missing setting.
- Open the org-level switch
From Setup, enter Chatter in the Quick Find box and open Chatter Settings. Confirm Allow customer invitations is selected. The Metadata API calls this same flag enableInviteCsnUsers.
- Grant the sending permission
Add Invite Customers to Chatter to a permission set and assign it to the people who run outside projects. Without it, a group owner sees no invite option at all.
- Flag the group
Create or open a private group and turn on Allow Customers, which writes CanHaveGuests on the CollaborationGroup record. A public group is not a valid target.
- Send the invitation
As the owner, a manager, or an admin, enter the outside email addresses and add an optional message. Salesforce writes a CollaborationInvitation row with Status set to Sent.
- Write down the end date
Note when the engagement finishes. Removing the member and deactivating the user is manual, and nothing in the platform will prompt you to do it.
The org-wide switch on Chatter Settings. Nothing about customers works while it is off.
Per-group, stored as CanHaveGuests. Only a private group can carry it.
The permission that lets an owner or manager send the email. Assign it deliberately, not broadly.
- You cannot invite an email address that already belongs to a user in the same org. Those people join the group directly instead.
- CollaborationInvitation supports delete but not update, so a mistaken invitation is cancelled by deleting the record rather than editing it.
- A permission set that grants Experience Cloud site membership will not pull a Chatter customer into that site. They stay outside it.
Keep the related term in your library so you can find this topic again.