I am NOT versed in prior versions, I cannot provide technical assistance in this, and can only offer a possible approach. I would NOT follow my approach unless you have the ability to reinstall ver 38. Anyway, here's my thought: - exit thunderbird - do a full backup of the proflie. very important - uninstall ver 38 and install latest version of release level - set up accounts, but do NOT include passwords (because I don't want you retrieving messages yet). - exit thunderbird - from backed up profile, copy the Mail and Imapmail folders into the new profile - restart thunderbird - import old addressbook

This would require redoing any settings or addons, but it has its benefits too. I post my suggestion only because I see you've been waiting a day for a response. There is a risk, but it may work ok. Again, I wouldn't attempt this unless you can readily restore ver 38. Good luck.

Thank you David for your input, I will be taking a look probably next week when I have more free time to concentrate! Your thoughts sound good to me, thank you John

Alternatively you can update Thunderbird progressively in stages with intermediate major versions until you get to the latest version. This is needed because Thunderbird does some "profile migration" actions between versions. You should go through the versions as follows: 38 -> 45.8.0 -> 52.9.1 -> 60.9.1 -> 68.12.1 -> 78.14.0 -> 91.13.1

Once you're at v91, do Help > About to get the latest 102 version (currently 102.7.0).

Intermediate versions are archived at https://archive.mozilla.org/pub/thunderbird/releases/

As Stans already pointed out, do a full backup of the Thunderbird profile prior to each step.

Thanks for the info I shall look into that this week, cheers!