MIT Sloan Management Review Article on When Communication Should Be Formal

Sometimes channels known for their speed and flexibility bog down organizations with errors and inefficiency.

Informality has become ubiquitous in modern organizations: The use of first names for everyone, including executives, is the norm, as are casual dress, flattened hierarchies, and self-organization. Business communication has grown more informal as well. We keep things casual so we can be fast and flexible and get things done. We email, Skype, Slack, and Yammer.