Was Emily Post an early adopter of technology? That’s the story in a new book by Daniel Post Senning, her great-great-grandson. She was so fond of her first-generation Dictaphone that she named it Suzy. “Emily Post’s Manners in a Digital World: Living Well Online” (Open Road) is a cross between a primer on social media and an old-fashioned etiquette book. The bottom line is “think before you act,” so some of it may feel simplistic to the digitally savvy. But Senning offers good reminders about being respectful: Yes, it’s OK to ignore a friend request on Facebook, and kids should remove both earbuds when talking to an adult.