You can add second phone number to your account, I do not think that you can add second email address. However you can add new host on your listing (if that what you mean). Just go to 'your listing' on your aibnb account and pick one of the listing you want too add new hosts. There is option 'additional hosts', you can add another hosts to receive emails and reply on your behalf.
Can someone screen shot how to find "your listings" and "additional hosts" page? Cant' find either on my account and am trying to add my daughter as an extra host.
I just contacted them to let them know that they should allow more than one email address to be used as it makes our owner response time quicker. I also chatted with a customer service rep bc I tried to add my second email as a "co-host" and it would not allow it. VRBO allows more than one email address and I really love their website and how easy it is to navigate. Maybe if we all sent them suggestions or feedback as they call it, they will make the change and make our lives a bit easier 🙂 Happy New Year!