Does a 'Mail' entry with the TB icon appear if you click 'More...' in the Share right-click menu?

https://bugzilla.mozilla.org/show_bug.cgi?id=309708#c46

Yes, it does. Any idea how to fix this?

Are you saying the TB icon appears next to Mail but you can't select it? Does the process described in the link work on your system?

Yes, that's correct. The TB icon appears next to the word "Mail" and the checkbox is ticked, but also greyed out (meaning I can't select it).

I'm not sure how the process described in the link relates to the issue I'm having...I have no interest in sharing iCloud-based files. I would like to be able to email files on, for example, my desktop, directly, rather than launching Thunderbird, composing a new email and attaching the file to the email.

My understanding is that what you want is simply not possible in OS X. It's probably related to the fact that this kind of operation only works in an OS that supports MAPI, which OS X does not. Consider the fact that even in Windows 10, the Share feature currently only works with the built-in Mail app, although sending files from File Explorer is possible.

If what you're saying is true, why does the feature work as expected using Apple's Mail app? In other words, if I set the default email client to Mail, I am able to share PDFs via email via the share menu easily. When I attempt to change the default mail client (to either Thunderbird or Outlook), this feature no longer works.

I spoke to Apple's customer service, who outlined that this is an issue with Thunderbird, hence why I posted in this forum.

Does anyone have a solution for this issue?