Confirm that you are a real person:
Click on the button to the left of "I'm not a robot".
Then a window opens with easy to be solved tasks.
Solve a few tasks until the "VERIFY" button appears and
then click on the button "VERIFY" to close the window.
If the task has been solved correctly, a green checkmark
appears and then you can "send message" below.
This is a action to prevent spam mails.