Communication can be challenging, to say the least! When you speak face-to-face, you can see body language, gestures, and hear intonation. If that same conversation is on the phone, you essentially miss the body language and gestures. If that message is conveyed by email, you lose the intonation as well; and if text, it can be even more obscure.
Many people shoot off an email without regard to how the recipient is going to receive or interpret the message. For example, one person I work with reads whatever is visible on the screen of her phone. Her staff knows that everything important needs to be in the first few lines.