That smartphone idea is a logistical nightmare.

With how long mail services are being delayed and, in the case of the USPS, at risk of being shut down, that's a lot of smartphones you'd need to send from address to address. If you have a 5-day film schedule, you're trying to get a single phone to 5 different locations with transit times of less than 24 hours, which is insane.

So bump up to two phones and have phone A mail to Monday, Wednesday, and Friday whilst phone B mails to Tuesday and Thursday. Trying to track even two separate phones through the mail system would be a nightmare. And it gets even worse when you consider the Monday guest may live in California, Tuesday guest lives in the UK, Wednesday guest New York, etc. What happens if you want two different guests on the same night? What about musical guests?