I followed your instructions regarding the 3 DWORD entries and changed them from 0 to 1.
After I restarted Windows Live Mail I still can't reply to my mail or forward and create mails.
Going back to the registry entries I see that all of the 3 DWORD entries changed again from 1 to 0.
Hello, De_Beig-
It's normal that the 3 DWORD entries change back to 0 after you restart. I have no idea why, but the problems I had were fixed, even with the "0"s.
My only comment is that the solution I posted on 3/26/2021, page 13, fixed my problems with Windows 10 at that time. You just have to go through each step exactly.
One other comment: Windows 10 just updated again a few weeks ago, and again it messed up my Windows Live Mail. While it seemed to be working correctly, I kept getting notices to sign in again. I then noticed in the upper right-hand corner, no one was signed in, even though my account was open and functioning. (?) So I went through the process of signing in again, (to WLM and my Microsoft account) and it was ok. You might check that you're correctly signed in. Good luck.