Installing eg:60 or earlier versions of TB over 68, running the addon email address crawler, then reinstalling 68, isn't advised as you may encounter backward compatibility issues with profiles. It's just not that simple any more.

You could download an earlier version of Thunderbird, http://ftp.mozilla.org/pub/thunderbird/releases/

but you would need to select the 'custom' setup option when you install older version, so that you can have an old TB installed in a different location from the default. Make sure the shortcut icon has suitable name so you know which is which and has 'Properties' 'Target' info setup has the -P added, so it invokes the Profile Manager allowing you to select the correct profile to be used with older version. https://support.mozilla.org/en-US/kb/using-multiple-profiles

Then create another profile with suitable name eg: OLD TB, and copy the contents of the existing profile over its files, so you can run an old version of TB on a copy of your profile with intension of using email address crawler to extract csv files. You would download and install the email crawler addon into the older version of Thunderbird. https://freeshell.de//~kaosmos/index-en.html#eac

If you have another maybe older laptop/computer, you could install an older version of Thunderbird, copy your current profile to that laptop to be used, download the email crawler addon and once you have csv files import them into the computer with the current Thunderbird.

There are products you can trial and pay for that claim they will perform what you require. After all, it takes knowledge and time to create the software, so you can't expect it to be free. Looking on google search there are Thunderbird email crawler software by Bitrecover and also Algologic IT Solutions. I cannot endorse either as I've not used them. I collect email address automatically as I send and also manually each time I get a new email where the address is required.

Thanks Toad-Hall. That is a very complete summary of the possibilities! I hadn't considered the possibility of paying for an add-on, (old habits die hard) but that seems like the most likely route to success. More speed to you. Ian

How do you collect email addresses automatically as you send?

kleiner.art

Thunderbird offers this and usually the default address book assigned to do it is the 'Collected Addresses' address book, but you can choose another.

If using versions 68*: Menu app icon > Options > Composition > 'Addressing' tab select checkbox: 'Automatically add outgoing email addresses to my' and choose an address book from the drop down list.

If using versions 78*: Menu app icon > Options > Composition scroll down to 'Addressing' section select checkbox: 'Automatically add outgoing email addresses to my' and choose an address book from the drop down list.

I have returned to this problem again. Although I thought ToadHall had suggested a useful solution, it turns out that (as far I can determine) all of the third party/paid solutions only work on Windows machines (or perhaps Apples). I have a Linux system. So no solution so far. I tried setting the config file to "extension.strictcompatibility = false" and then installing an old version of Email Crawler but that didn't work either. Have I missed something somewhere?

I think I have this mostly solved! There is an extension called Copy Address by ctrlxc It copies addresses to the clipboard. I just selected all of the emails from which I wanted to copy the sender's address (ctrl A); clicked on Copy Address and then pasted the clipboard contents into a text file where they have appeared separated by commas. A csv file! I can work with that.