Hi there Sandy
We have been Superhosts for sometime with a couple of properties and my experience is that all messages, using the Airbnb facility get through. It is recommended that you use the Airbnb site and not your personal email and I have never had a problem with any communications.
If you were worried you might like to ask your guests a question with a timeframe eg: "can you please confirm your arrival time two days prior to arrival" etc However I would not be fussing about this - everyone is busy and some will come back and say thanks for the information and other acknowledge it just before they arrival.
As long as you are providing the correct information to your guests ... relax and enjoy ... it is a lovely business to be in. Hope this is of assistance.
Regards and best wishes - Lesley, Picton NZ