When I set up triggers, does it send to the guests email address or the discussion thread through the channel?
Welcome! Be patient - it's a process but well worth it.
If you have a personal email address entered on the Booking Overview Page for the guest, a trigger will go to that email. Anything you can do to get the guest's direct email is good because if you send triggers through the randomized email address provided by AirBnB some of your content may be blocked and in some cases no message at all will get through.
While it is good to communicate on the Booking Platform, particularly if you think you may have a problem with the guest or you just want to CYA, trigger messages seem to work better going directly to their personal email.
Also - try to get a verified email set up to help keep messages from going to spam:
it depends how you set them up. for example. the template sent to airbnb guest when booking comes in that gives them link to e-sign rental agreement and asks or ID is sent o their airbnb-disguised address.