Handoff new mail does not work

Hello all,

I was giving handoff a try after quite some time. I am using Mac with OS 10.12.6 and iOS 12.0.

The first thing (and the one I would use for handoff in first line) is to write a mail. But it doesn't work. Here are my tries:

1. when I start to write the mail on the iPhone, I see the handoff symbol on the dock. When I click on it, mail opens, but the main window, bot the mail window. The handoff symbol in the dock then disappears. When I go on writing mail on the iPhone, the symbol appears again. But clicking on it does nothing except that the symbol disappears.

2. When I start writing mail on the Mac, I get the option to continue writing on the iPhone. It then tries to open the mail window on the iPhone but fails with "handoff cannot be finished" (I don´t know the exact wording in english).

I tried handoff with safari and notes, and there it worked. So is this a bug in mail or am I doing something wrong?