I think there may be significant changes in the profile that would stop this old profile from working with a new Thunderbird. And I'd have to warn you that the new Thunderbird will probably appear to be alarmingly different from that old version.

I think I would install new Thunderbird, set up the account(s) by hand then copy in the corresponding mailbox files from the profile from the old machine. Whatever else has changed, I believe that the fundamental mail store file is the same as it ever was.

If the accounts in question are POP (and I'd recommend keeping them the same in the new installation to minimise the shock of change) then you could copy the old files into the new installation's mail folders. I'd do this in Windows Explorer and not as a Thunderbird function.

I'd also review the old and new Thunderbird and do what I could to make the new one look and behave like the old one. One insurmountable change is the introduction of tabs.

You could find an installer for an old version of Thunderbird but I would be reluctant to advise anyone to install old software with known security weaknesses, and it's hard to say just how many versions you could change without hitting some incompatibility issue.

You could install the same version she already has, and in fact you could probably just copy over her existing installation of Thunderbird. But I'd have to repeat the caution about the weak security of old software.

Hi there,

Thanks for the quick reply and very helpful info.

One last question if I may.

As this switchover to a new PC is going to take some time, I thought about installing a new version of Thunderbird on here current machine so that she could get used to it.

Are you able to install a new version of Thunderbird on the same machine without it wiping out the settings and files of the previous installation?

Thanks again.

I do not suffer the same concerns Zenos does about upgrading the profile.

There have been significant changes, but the profile has not changed as much as may be assumed. The fundamental of email storage in mbox files have not changed since Netscape was running things.

On the whole the profile should upgrade, although there would be a couple of losses I would expect, not the least being passwords would simply be lost. There have been a number of updates to the storage process for passwords, and while I understand all the code to upgrade profiles is still in there. I would expect them not to come out the other side. They have been problematical almost every time the format changed.

I would suggest in the first instance simply making a backup of the profile and trying to apply the latest version. It will probably work without incident. If there is an issue then you have a backup to replace it with.

With Thunderbird shut down, windows key+R. In the run dialog type %appdata% and press enter. This will open Windows explorer in application data. Copy the Thunderbird folder and all sub folder to your backup device. Backup made. Right click both copies of the thunderbird folder, the original and the backup and select properties. Check the number of files and folder matches.

OK guys, thanks for the advice.

I am going to attempt to do this over the weekend.

I will report back with the results.

Thanks again.

OK Guys, the result was a resounding success!

I have laid out my plan of action below for anyone interested in achieving something similar in the future,

1) I can confirm what both Zenos and Matt said - emails stored in the local folders within very old versions of Thunderbird profiles can be copied to newer versions of Thunderbird.

I actually tested this first by copying the local folders from the old WIndows XP Thunderbird 0.7.3 install, and installing them onto a Windows 7 Thunderbird 45 profile on my laptop without any problems at all. (After backing up my own local folders first of course).

So thanks to both Zenos and Matt for that info.

2) I then backed up the Thunderbird 0.7.3 profile which included the local folders which needed to be copied over to the new Thunderbird install.

3) I decided to set up the email accounts from scratch, mainly because the old profile seemed somewhat corrupted with old passwords stored for email addresses that no longer existed.

Furthermore, it seemed unable to remember passwords that were still in operation.

I therefore uninstalled Thunderbird 0.7.3 and then installed Thunderbird 45.

4) I then spent the rest of the time setting up the email accounts, moving the local folders into the new profile, as well as making the new install look as similar as possible for the person in question,

So, she now has a brand spanking new Thunderbird will all of her old emails taken from her old Thunderbird profile.

Thank you once again Zenos and Matt for your help.