All emails should be 2 lines only, is something I learned when I started working in an office. For example,

  WHAT YOU ARE SAYING

  WHAT YOU NEED FROM YOUR AUDIENCE (RESPONSE OR DECISION OR ACTION ETC)

As time goes on, often I say (to myself) "forget that", and write all the detail that is needed anyway, even in email. But only for audiences that may care about the detail (or otherwise are safe to skip the email altogether).

But who uses email at work anymore, anyway, right? I guess some organizations.

I prefer adding the detail; if it's going to turn into a phone call anyway I might as well have a script ready to go.

Most orgs still rely heavily on email, and most emails should be more than two lines to be useful. If it's only two lines, Slack it.