I still stand behind the two suggestions in the second paragraph of that post; first, address your readers as you would when talking to them; second, follow the lead of respected coworkers. After nearly a decade since that post, I would add a third: walk a mile in your readers' shoes. If they merit a communication from you, they deserve the respect that comes with it.
Yes, the world has gotten quicker, and yes, we communicate more informally with people. Most people do not get offended when total strangers start an email by greeting them by first name, as in Hi Phil. If they did, they'd be angry most of the time. But such a familiar greeting gets under their skin like a stubborn tick when writers, regardless of their age, are selling them. And it makes them hit the ceiling like a loose spring when they are receiving customer service for the first time.
If you're unsure of the best way to greet someone, err on the side of formality. Better to be called a stuffed shirt than to be called rude. Start with Dear Dr. Mailer, Dear Ms. Miller, or Dear Mr. Muller. Then wait for your readers to break the wall of formality, and let the first two tips from that 2009 post kick in.
