@Shamil12 Don't add an email to the site (and it's likely not possible.) AirBnB discourages off-platform communication, and will actually block any email address or website you try to share. Keeping communication on the platform protects both you and your guests. If you ever have issues, you'll understand how and why.
As to the gift, I've gotten really wary of alcohol in general. It's so easy to offend these days, and I hate the thought that I might leave a bottle of wine for someone in AA, or with similar issues. But....they have to be over a certain age to book on this site, so I wouldn't ask, even if you decide to leave wine. Depending on your property and their profile, the below may apply:
Guests between 18 and 24 can create their own personal Airbnb account. In a few, specific countries (Canada, US, UK, France, Spain), guests under the age of 25 are restricted from booking an entire home if they live locally and don't have at least 3 positive reviews with 0 negative reviews.