@Punam0
I agree that this would be very useful, but in the meantime...
When a guest isn't getting back to me and it's the day of their booking, or the day before, I would text them to check if they got my messages. If that fails, I call. If still no luck, I call Airbnb and ask them to try to get hold of the guest. I would not rely on the Airbnb message system alone if time is running short as unfortunately, quite a few guests book and then never check the message thread again, especially if they don't use the App. I'm not going to hang around indefinitely waiting for a guest who may or may not show up.
I've had Airbnb cancel reservations for me because the guest is being non-responsive. That's always an option if they've instant booked. In one circumstance, the guest had booked and then I never heard from her again. By the day of her arrival, neither I nor Airbnb had been able to reach her by email or on her phone. So, they cancelled the reservation and I got paid in full. She never showed and I hope that she was okay. However, sometimes people's plans change and, when they realise they are not going to get a refund, they don't think it's necessary to inform the host.
For any other circumtances, I try to keep all messages on the Airbnb system. If there's a problem down the line, the case manager will need to see this.