I used to work in an email heavy industry, so people who don’t use email or more specifically what I call “threading” right.

Changing the topic (so that the discussion no longer relates to the subject line), replying to add someone in without reattaching the relevant attached files, not using redirect email functionality, including screenshots that either lack relevant information due to poor cropping or forces the recipient into retyping its contents by hand all make email super annoying to deal with. And what’s with being expected to confirm you received each and every email? Ever heard of read receipts?

Also, people who don’t read error messages. As a web developer (or more broadly “computer person”) I cannot count how many times someone has sent me a picture of an error asking me what to do. 90% of the time the error itself tells you exactly what to do. Why do I need to read it for you?