Sometimes its necessary to send an email that’s like a memo. A quick update that may just be informational and not require any action. Dropbox has done a great job of doing that here in this email. It’s clear who the email is from and why its being sent.
Personally I like a little humor or humanity in an email like this. I love seeing when people don’t take themselves too seriously. Maybe a link to a gif, or something beautiful because when you read the news its nice to see something that makes you happy.