Assuming Windows, this should work if the profile is in the default location:

This is how I do it: - exit thunderbird - copy c:\users\<yourid>\appdata\roaming\thunderbird to an external drive - on computer B, install thunderbird and exit - copy the backed up Thunderbird folder to computer B on appropriate drive:\users\<yourid>\appdata\roaming to overwrite the existing thundebird folder - restart thunderbird on computer b and all should be there.

Hi David,

Computer A ( Windows 10 Pro ) contains a live Thunderbird 115.7.0 instance and data ( folders, emails, attachments).

Computer B ( Windows 7 Pro ) contains an old static Thunderbird 45.4.0 instance and data ( folders, emails, attachments ).

If I keep the T45 static instance and data on B, can I install a new T115 instance on B with its message store being a copy of the live data from T115 on A?

I want to use T115 on A for live email, archiving it periodically to T115 on B.

How do I switch between the TB instances and data on B?

I would keep T45 and its data on B as a static backup.

Thank you!

That's quite different from your original post. You're propose a solution, but I'm unclear of the problem. If the intent is just to archive, you could specify archive to the other drive from computer A. If the intent is to have backup in case of problems, copying the profile itself periodically would accomplish that. If the intent is to have fully duplicate setups to allow use of computer A or B, then install 115 and accounts should be IMAP, and I would suggest exporting the message folders from T45 and including in the new 115 profile. What am I missing?

I'll try to explain the problem in more detail:

All of the email accounts on TB115-computer-A ( T115-A ) are POP on purpose, so emails are downloaded and stored on a local machine rather than on third-party servers.

The T45-B store is an ancient version ( from Windows 7 ) that was upgraded and expanded through multiple TB upgrades and daily email usage on a series of computers. That evolution is the current T115-A store.

So I'd like to keep T45-B instance and store as a standalone setup, for rare cases when the T45-B data state might be needed. I could try opening a copy of the T45-B store with T115-B, to see if it works.

T115-A is the only client allowed access to the third party email servers.

I'd periodically backup the T115-A store to B, for example in separate B directories, like so: ComputerB\C:\Users\<user>\AppData\Roaming\Thunderbird\Profiles\A-BACKUP-2024-01-01 ComputerB\C:\Users\<user>\AppData\Roaming\Thunderbird\Profiles\A-BACKUP-2024-01-08 ComputerB\C:\Users\<user>\AppData\Roaming\Thunderbird\Profiles\A-BACKUP-2024-01-15

Ideally, the T115-B instance can easily render each of the above backup stores on B.

Maybe there's an easy way of pointing T115-B to the different stores in the above example.

I don't know how to use the TB Tools menu to do any of the above.

Are these all I need? Tools \ ImportExportTools \ Export profile Tools \ ImportExportTools \ Import profile

I have seen some problems exporting the profile with menu-driven tools. A simple way to access the backed-up profiles would be to use help>troubleshootinginformaition, scroll down to 'profiles', click 'about:profiles', and then click the 'create profile' button in upper left, click next, enter a name for the profile, and then click the browse button to locate and select one of the previously copied profile folders.

Hi David,

I followed the instructions in your last reply, for switching between backed-up profile folders, from a fresh installation of TB on another computer.

I backed-up the existing 8GB /profile/xyz folder to another computer on the LAN ( C3 Win10pro ). Installed TB 115.8.1 64-bit on C3 in the default location. On TB-C3 used help/troubleshootinginformation/profiles to load the profile.

All messages, attachments, and accounts appear to be on C3, a redundant TB instance.

Thank you again !

Thank you for sharing the good news. Nice to hear.  :)