Volumes have been written about when not to write. If you have something difficult to say, it’s best to say it in person, or so the advisors will tell you. Email (that’s how most business writing occurs today) is certainly not an ideal medium for tough conversations; it can be cold and impersonal. If you have a good relationship with someone, you want to temper your difficult conversation with personal signals; empathy is easier to express in person. But there are times when writing is the best medium.