Editor’s note: As an etiquette guide, this article is based on opinion. It’s goal is to create a standard.
These days we have so many communication options it can be hard to know which one to use. I’m going to try to give you some guidance on that.
Phone calls have become the primary communication method for many people and there was a time when that was appropriate, but not anymore. It’s fast but it’s also an imposition and so insecure it may as well be public. Leave the phone calls for when you need an immediate response or intend to carry on an extended conversation. If waiting five minutes for each response isn’t a problem, choose another method.
Any form of SMS, including iMessage, are exceedingly casual so should never be used for any communication where it matters how you present yourself. Its asynchronous nature also means you need to be ready to wait a little while for a response. It’s best used for short exchanges between friends, family, or colleagues.
Instant messaging services, like the typical chat app, are only ever to be used for casual conversations you carry on while doing other things. It’s a good way to keep in touch with people you don’t get to see as often as you’d like or as an alternative to calling your coworkers or walking over to their offices or cubicles.
Letter writing is somewhat of a lost art. It used to be common but is now largely unused. The simple rule of thumb is, if you’re unsure, a letter is a good idea. The only more intimate way to communicate is face to face but a letter allows you to craft your message more carefully, and poetically. If you don’t expect to see someone for an extremely long time if ever then there’s nothing better than regular letters.
Face to Face
It’s not so much a question of when face to face interaction is appropriate but when it’s not. It’s the best option overall so it should only be skipped if it’s impractical or you require greater subtlety.
The nature of social media means it is in fact broadcasting. For that reason, you should only use social media for things you wouldn’t mind telling to everyone you know.
I left this one for last because it should be your default. If there’s no reason to choose another method than email is the right one. Just remember you should reply no later than early the next business day if at all possible.
Edit: I almost forgot the two common communication methods that need to completely die; voicemail and fax. They’re both horribly outdated and have no place in the modern world.