Right-click a file, Show more options, Send to, Mail recipient, will open a new TB message with the file attached, if TB is the default mail client.

The right-click context menu in Explorer on my new Win11 machine did not include Thunderbird as an option. In Win10 you used to be able to go to default settings and under email select TB as the default and that would fix things. In win11 there is no longer a default for email, but rather for Mail. Under that you can set TB as the default under .eml and MAILTO, but under MS-UNISTORE-EMAIL and OUTLOOKMAIL TB is not an option.

So then I did some searching and found that if I added TB in the following folder %APPDATA%\Microsoft\Windows\SendTo\ as the MAIL Recipient and also as a shortcut to TB, then I could get TB in the context menu, but when I select it nothing happens. If I tab over to TB it is open but no email is started and no attachment appears.

Is there a fix for this or is this another nasty win11 problem?

The method in my first reply works here in W11. The default app for MS-UNISTORE-EMAIL and OUTLOOKMAIL is the Windows Mail app. Maybe you have to declare TB as the default email app in TB Settings/General, System Integration, Check Now...

I did that and rebooted.

Also because of what I had done I had both Mail Recipient and a shortcut to the TB program in the %APPDATA%\Microsoft\Windows\SendTo\ folder. Then things worked, but when I right clicked I had both a Mail recipient.MAPIMail and a Thunderbird option come up. Only the MAPI option worked. I went back to the APPDATA folder and deleted the shortcut to TB and now on right click I just get the MAPI option and it works fine.

Thank you.