To create a listing group, browse to the "Settings" page.
Scroll down and click the "+ Add Group" button.
Give your listing group a name.
Add the listings you would like in the listing group.
Click the "Save" button.
You will now see the listing group available under the "Messaging" menu at the top of the Host Tools dashboard. Any message rules added to this listing group will send to guests staying at any of the listings in the listing group.