I thought the new UI was going to be ok, but we are really struggling with
it.

Especially and specifically when viewing a message where the conversation is
threaded:

Things I can't do:

1) Forward, Reply or Reply to All.
2) Resize the different message windows
3) Take an attachment from a message and open it in the app it's supposed to
open in. (Clicking the conversation tab and then scrolling to the message in
question then double clicking the attachment opens it correctly but is more
clicking)
4) Take an attachment in a message in that view, and drag it to a new
message need to use the process in 3) to do this.
5) Can't revert to the old message view, clicking 2014 defaults doesn't
help.

Help!