Still writing thank you notes by hand
My kids think I'm ancient but I make them write thank you notes after birthdays and holidays. Handwritten. I don't care if it takes 20 minutes. That's how you teach gratitude and respect for other people's generosity. My son complained about it until he saw his grandmother's reaction getting his note in the mail. Now he gets it. Some traditions exist for a reason.
My kids groan about it too but I catch them being thoughtful about what they write. You're teaching them something real.