Give this a shot…
- Go to Windows Settings/System/Default Apps.
- Make sure eM Client is the default email app.
- At the bottom of that page, click on “Set defaults by App”
- Click on eM Client.
- Click “Manage”
- Click each of 1st 5 items and choose eM Client (not sure what the last 2 are for so I just left it alone)
This worked for me, Windows 10 current version, eM Client 8.1.1060