Yes, that is normal practice. I think part of the reason is if you (or anyone receiving package) claims to have not received it and the carrier has to investigate they have to actually confirm with recipient if it was or was not recived. I had this happen before when I had a buyer who hadn't received package, Canada Post needed both phone and email as they had to check with them. Since a lot of people don't answer their phone these days they like email as back up. In my case the buyer responded and all worked out.
If you look at your order details for sending to him you should also see his phone number there. I checked on a few of my packages going TO the US and they all have phone numbers (at least that shows to me) none show email though, perhaps email is preferred but not enforced.