Send To Context Menu - Remove or Restore Default Items

What Send to options do you have?

Well, that looks good other than "Mail recipient" missing.

Go ahead and post a screenshot showing both of your Sendto folders from Option One to see what they look like.

C:\Users\Default\AppData\Roaming\Microsoft\Windows

C:\Users\(your user-name)\AppData\Roaming\Microsoft\Windows

Yep, it's Thunderbird causing it. You can tell by the icon that you have for your Mail recipient shortcut instead of the default one.

Check to make sure that Thunderbird is set as the default program with all of it's associations.

https://www.sevenforums.com/tutorials...ociations.html

If that doesn't help, then other than selecting to attach the files from within Thunderbird, you might see if uninstalling and reinstalling Thunderbird may help.

If you only uninstall Thunderbird, does it work properly afterwards?