Previously Airbnb hosts could contact guests through the email alias feature, which created an unique and anonymous email for guests — something like Now this option is no longer available to hosts by default.

I am no longer getting the email address of guests when they make a booking. I have a large amount of information that I used to send to guests when a booking is made, with attachments and photos, far too much for the Air BNB message box. I've had really good feedback on this - why has Air BNB deleted guests email address from the info sent to hosts?

For privacy reasons the email link has been removed

However, from a computer hosts can reactivate email option thorough this section If you don't have access to the Professional hosting tools you can activate it here