It was handled rudely. Sadly there are a lot of rude people out there.

Did he follow up with suggestions how to improve or training opportunities for you? Is he inexperienced or is he just in general rude person? I mean everyone makes mistakes but it’s a common knowledge to start with a positive message and follow up negative messages with improvement suggestions. In fact managers must provide suggestions to struggling employees.

I bet he got in trouble with higher ups because his employees didn’t meet their goals yet he simply takes it on you all instead of following proper procedures.

“I had many wonderful bosses and YOU aren’t of them”. I know you can’t really reply like this but it’s kind of tempting lol

I’d follow up asking for Improvement suggestions. In the email. In writing. I’d also save rude emails with no suggestions, it might come handy in the future. You never know