Due to a limitation on Misterb&b, messages sent from Misterb&b's inbox will not arrive in Guesty's Inbox when connected via Rentals United. You can sign in to your Misterb&b account to communicate with guests.
Alternatively, you can add the guest's private email address to the reservation. This will allow you to communicate with the guest via Guesty's Inbox. Learn more.
If you do not have the guest's personal email address, you can ask them for it via your Misterb&b account.