WIkimedia (Echo) notifications literally have no branding and are very "frugal" in their design compared to typical HTML notifications (see below a few examples).
See T90067: Email notifications should include as much context as is feasible so i can just read my email and not visit the website. regarding how to improve this in other ways, as well as email stuff at https://www.mediawiki.org/wiki/Echo_(Notifications)/Bug_triage .


