This would be a great example of a situation where better word choice would be helpful. /s Seriously though, the term that comes to mind is “Fleish-Kincaid readability score” which basically says how educated you would have to be in a language to understand something. Professional documents should get a score around an 8th grade reading level, so the issue with your coworker is that they aren’t accounting for readability in their emails. Isn’t it comforting to learn that term though? Your problem is not only not new, it’s common enough that people have a word for it and it’s a big enough issue that MS word has a feature built in to give you a score on it. Honestly knowing the meaning and history of words is the only way I can keep track of this crazy, mixed-up world we live in.