The list is the "registered" profiles, not some list of files in the file system. So you have to create a new profile in the location you have placed your old data to get it into the list, and get to use it.

I was suggesting the profile backup and restore, but it looses all your passwords, so is next to useless. a year after launch and it is still a cripple.

Of course there is just a most basic way. Go to the show profile button in the troubleshooting information on the help menu. When the explorer window opens shut down Thunderbird and paste the contents of your old profile into the new folder. (note I said contents, so don't past a copy of your old profile folder inside the new one) It will get lots of "replace" errors which you need to accept to get your old data into the new profile, but it "just works" because it is so crude.

If I understand you correctly, what you are suggesting can be done in Explorer without going through Tbird help, correct? In other words, - go to C:/Users/(MyUserName)/AppData/Roaming/Thunderbird/Profiles - copy all the files and subfolders of the profile I want to use (including all the address book, extension, history, "impab" files, etc.) - paste those files and subfolders into the default profile folder - say yes to all overwrite warnings

Is that right? If so, I have 2 further questions: 1. What is the difference between the "default" and "default-release" profiles? Does it matter which one I make the default before I paste over it? 2. Tbird has already imported all my 1000's of Gmail messages into the Inbox of the default profile. On my old system those messages were organized into dozens of Inbox subfolders, which were populated through message filters, and local folders. Once I overwrite the new profile with my backed-up profile will all that be reproduced? I don't want to end up with 1000's of messages in my Inbox that are already in subfolders (or deleted from them).

Really I have one more question that I hesitate to ask: Thunderbird has been around a long time. Why isn't there a simple way to do this? Like a startup switch, "Create new profile or Browse to select existing profile"? I would have thought it was obvious that Thunderbird users who upgrade to a new computer might want to transfer their entire profile as is. I never expected to have to do all this file manipulation to accomplish it.

There are easy ways to move a profile and Thunderbird Help Articles to use - but it depends upon what you mean when you say " I backed up my old profile (16.4GB) "

Typically I would have done this:

On old computer

• Exit Thunderbird
• Access C:/Users/(MyUserName)/AppData/Roaming folder
• Copy the 'Thunderbird' folder to external device

On new computer:

• Install same version of Thunderbird that I used on old computer.
• Exit Thunderbird
• Access : C:/Users/(MyUserName)/AppData/Roaming folder
• Delete the default created 'Thunderbird' folder
• Paste the copied 'Thunderbird' folder into the 'Roaming' folder
• Start Thunderbird

But if you only backed up an actual 'profile name' folder then you can do one of the following Option 1: On new computer

• Install same version of Thunderbird as used on old computer
• Run first time to create a new default Profile
• do not create any mail accounts because you want to use old profile.
• Immediately Exit Thunderbird

• Access C:/Users/(MyUserName)/AppData/Roaming/Thunderbird/Profiles folder
• locate the new profile name folder and open it to see contents.

• Locate the old profile - open it to see contents
• Copy all the contents - everything in that profile name folder

• Paste them into the 'new profile name' folder making sure to over write everything OR delete everything first and then paste in the copied files.

This option 1 process is using the current default profile name foder meaning you do not have manually mess around trying to edit the 'profile.ini' file which if you get it wrong can mess up things.

Option 2: On new computer

• Install same version of Thunderbird as used on old computer
• Run first time to create a new default Profile
• do not create any mail accounts because you want to use old profile.
• Exit Thunderbird
• Access C:/Users/(MyUserName)/AppData/Roaming/Thunderbird/Profiles folder
• Paste the old copied 'profile name folder' into the 'Profiles' folder.

Now use Thunderbird to auto select detect and use that added profile by createing a new profile that points to it.

• Start Thunderbird
• Menu icon > Help > More Troubleshooting Information
• Under 'Application Basics' section
• Near Bottom - Profiles - click on 'about:profiles' - it opens in new tab

• Click on 'Create a new Profile' buttpn
• Click on 'Next'
• Enter new Profile name : Default User is a good name so use it
• Click on 'Choose folder'
• Now browse to C:/Users/(MyUserName)/AppData/Roaming/Thunderbird/Profiles folder
• Choose the profile name folder - the old one you copied over.
• Click on 'Select Folder'
• Click on 'Finish'

This auto updates the 'profiles.ini' file and you will now see the new profile in the 'about:Profiles' tab

• Click on the 'Set as default profile' button

Exit Thunderbird Wait a few moments and then start Thunderbird It should open and display the old profile.

So the method you use depends upon what you backed up in the first place and whether you are comfortable editing folders or whether you just want to use Thunderbird to locate everything.

Thanks for your help. I turned my old computer back on, copied the Thunderbird folder and then pasted it into the new Roaming directory and that seems to have worked. I did not see any option on the Mozilla site to install older versions of Thunderbird so I just left the version that had downloaded in the first place and it seems to be working with the old profile - all the Inbox subfolders and local folders loaded and populated and the filters seem to be working. So I think this is resolved.

Thanks for your help. I turned my old computer back on, copied the Thunderbird folder and then pasted it into the new Roaming directory and that seems to have worked.

Good to hear you are now ok. Could you mark my previous comment which had the info that helped as a 'Chosen Solution', this also makes it easier for anyone with same issue finding a solution. Thanks.