Yes, email is harsh. I know. We were never in the habit of talking on the phone much, so that would have been awkward. And I didn't want to hit him with it at rehearsal tomorrow face-to-face with the other guys there - too confrontational. Most of our band communication has been via email, it's the way we work.
I took my time, phrased something really nicely, and got my wording just right. Face to face, or via a phone call, I'd say something he'd take issue with. I wanted it to be very clear and simple. In the "old days" I would have written him a letter, so I've just done the modern equivalent.