It works here as expected in TB 60.3.2. Does it work if you Help/Restart with Add-ons Disabled?

No, that makes no difference.

In Tools/Account Settings, under Composition & Addressing for the account, do you have 'Automatically quote...' checked and 'start my reply above (or below) the quote' selected (see picture)?

The automatically quote message option is a different behaviour. That just inserts the whole message into the reply as a quotation. That's not the behaviour I'm concerned with.

It's the ability to just select some of the text to reply to and then insert as a quotation without needing to copy it.

I realize autoquote is not your issue, but the quoting of selected text as it functions on my setup may depend on the autoquote settings. I find the expected behaviour works whether or not autoquote is enabled, but sometimes switching a setting off and on resets it to the correct outcome.

If you are unable to find a way to correct your setup, try with a new profile, created by Profile Manager. Windows key+R and type thunderbird.exe -p Set up an account and see if it works properly. You don't lose any of your original profile and can return to it via Profile Manager.

Having now dug deeper it looks like the problem is that a fantastic add-on AutoCopy 2 has been disabled on the latest versions of TB.

Curious to know what you've got on your system sfhowes that enables the same functionality.

Maybe the answer is to try and back track a few versions and stick with an older working version, but I'm nor sure if I'll loose my mail base trying to go backwards.

I don't have any composition-related add-ons, but I have noticed some unexpected behaviour, even in safe mode. I received a message, composed in the W10 Mail app, that doesn't contain more than regular text. When I select the last line, then Reply, the entire message is quoted, not just the selection. Selecting any other portion of the message results in only that part being quoted. Now, it's well-known that even plain text sent from MS email clients adds a lot of hidden code, so I suspect that is causing TB to quote more than just the selection. The problem doesn't appear with mail composed in TB. Note also that nothing changes if I have the AutoCopy 2 add-on installed and enabled - which doesn't work anyway in TB 60.

So, I suggest you check the source (Ctrl+U) of messages that aren't quoting properly and look for the User-Agent, or experiment with selecting different parts.

Blaming the incoming messages isn't right. It seems clear now that the problem is that AutoCopy 2 now doesn't work. Hopefully the author will update it. In the meantime I think it easier to try to revert to an older version of TB that does support the add-on, as nothing recently added has been of value to me, but loosing AutoCopy 2's functionality is a major annoyance.

rhossydd said

It seems clear now that the problem is that AutoCopy 2 now doesn't work. Hopefully the author will update it.

I select some text, click reply and that is what is quoted. I never heard of this autocopy add-on until today, so it is not the provider of such functionality. Until you can get past that I doubt this topic will make progress.

Having now looked at the add-on I really do not see any functionality it adds to Thunderbird except paste into search bar.

Search is on a right click context menu. Thunderbird has no location bar

No, you're missing what Autocopy2 does. It's more sophisticated than the simple select>reply function which does work here.

It allows any selected text to go automatically to the clipboard, it makes replying with multiple quotes far easier. I don't use it with search or anything else, just fast selected quotes. If you'd worked with it, you'd understand why it so valuable.