Guests not receiving automated instruction emails?

Hi Team,


Very strange one. I get phonecalls or emails from pretty much every Booking.com guest just before they arrive because they havnt recieved my automated email outlining the check-in process. 


It's very frustrating as I can see the message has been sent via the Pulse App. 


Do they actually recieve a Booking.com email when I send this via the app? I really don't get it. 


All other platforms work fine. I use hospitable to generate the automated check-in email 4 days before their arrival.


Anyone else having the same issue?