Hi Tony_Raven,

This may help you.

https://support.mozilla.com/en-US/questions/892231

Thanks, I looked at that but that was about another option of Live Bookmarks, not automatically creating an RSS subscription in Thunderbird from within Firefox. I can create the feed manually but puzzled that the automatic option seems to be there but does nothing.

Options -> Applications -> Web feed ->Select Use Thunderbird from drop down menu {or select "Use other" option and browse for thunderbird.exe if it doesn't exist.}

Click View Feed XML on the feed subscription page.

Nope, tried that too and all it does is short circuit the pop-up window i.e. in Firefox instead of getting the feed in a browser window with the "subscribe to this feed using Thunderbird" option it jumps straight to TBird - but with no feed visible anywhere. Its just not transferring the information between the two programmes.

Have you tried looking for the feed under Blogs & News Feeds heading in Thunderbird?

Yes and it only has the ones I put there manually.

Maybe you should try to update Thunderbird to the latest version,if it's not. Btw,You can try this

feed:http://something.com/rssfeed.xml

or

feed://something.com/rssfeed.xml {replacing http:// or https:// by feed://}

in Firefox browser.

See above. v7.0.1 is the latest version of Thunderbird (and Firefox)

Reading the feed in Firefox is not the problem. Manually setting up the feed in Thunderbird is not the problem. The apparent facility to one click add feeds into Thunderbird from Firefox not working is the problem.

Actually, applying the feed url in such format opens up Thunderbird and loads the feed from the given feed url on it.