Email.

Use email when it’s more convenient than other forms of communication. Most often that is the case. But a company in which everybody is hunched over their emails and screens becomes more introverted than extroverted. As well, limit collective emails à la ”I can’t find my pen, have you seen it?”, or ”Have a look at a gross porn-image I found online”. And remember the single most important difference between a postcard and an email: You may still retrieve the postcard by knocking over the mailman, but the email is irrevocable. And this is particularly pertinent if you’re a bit irritated and push “send” rather than ”forward”. See “Social media”.