An iCal provides a standard way to allow one application to view and display calendar data from another application. For example, you can use an iCal link to import your Booking.com reservations into Host Tools. Host Tools can then block your calendars in Airbnb, VRBO and Houfy for the dates booked on Booking.com.

You can automate messages to any reservation imported via iCal.  Unlike reservation imported using a linked account (Airbnb VRBO, or Houfy), messages sent to reservations imported via iCal links will be sent messages via email.  To do that you need to add the guest's email address to any reservation imported via iCal links.  All emails set to the guest will have your name as the from name and your email address as the reply-to email address.