Obviously this is just another fake holiday invented as a marketing scheme. If you really want to help small businesses, then don't pay with an American Express card which charges them much higher interchange fees than other credit cards, and especially high compared to using a debit card.
Someone somewhere has got to pay the bills, and the current state of "free" email providers isn't good. Good email is worth paying a small sum for. So the best solution is to register a domain name so you're never tied to one provider (say $15 to $20 per year), and then sign up for a reasonably-priced commercial email service. Fastmail are good, as are Proton Mail. I'm an Apple device user, so I use my domain with iCloud+ which only costs a dollar a month.