I recently upgraded from Mavericks to Sierra. The new Mail client bugs me: My main problem is a change in the way it sends clipboard copies of what was in the Terminal app.
Previously, when I sent a clipboard copy of my terminal in the old Mavericks Mail client, it kept the original formatting (i.e. the white characters on black background copied from within the terminal) and when somebody received it, it was as I sent it (i.e. white on black). This was a very convenient way to show what was copied from the terminal.
Now with Sierra's mail client, the background is changed to white so that the white text cannot be seen by the recipient. This happens even though at my end it looks fine (i.e. white characters on a black background).
How can I keep the original formatting as I copy it into Mail, so that when it's sent it is received at the other end still showing the black background?