I understand. Some guests want to be completely sure before booking and would like to see the place. However Airbnb advices otherwise and doesn't promote having guests over without a booking. As I had mentioned, 1) For your saftey, as you do not want a thief disguised as potential guest reach your apartment. That'd be bad for you as well as the company's reputation and 2) Airbnb wants to eliminate alll possibilites that would allow guests to book directly with the hosts in order to avoid the service charges and taxes. That's bad for the business and the beautiful eco-system that they provide us.
TIP: You've managed to send you send the mail-id this time but be careful, Airbnb has auto scanners that might detect this and flag your lisitng and send you are warning mail. It's best to avoid sharing sensitive information prior to booking, altough I completely understand your case and agree that the message app is not the best tool for hosts and guests to communicate.