Anger alienates.
Always.
Communicating with anger rarely solves a problem, and can often make it worse. As and educator, I believe that anger is never a tool that teaches, so if possible, I never want to use it at all.
This goes for all types of communication, and double for written communication, when tone is so often read angrier than intended.
If you must communicate in anger, go ahead. But don’t expect to turn many minds, to inspire many souls, or to teach many minds while you do.