As long as it works, all is good. Here is another way: - exit thunderbird - copy profile to wherever desired - click windows key and 'r' key and press enter - enter thunderbird.exe -p and press enter - you are now in profile manager. click 'create profile', then click next, then enter shortcut name, then click 'choose' and then locate and select the profile and click finish (You can also do these steps after copying profile by clicking help>troubleshootinginformation, scroll down to 'profile folder', click 'about:profiles' and then click the above mentioned 'create profile' button and continue. - when done, you can remove the old profile at appdata\roaming\thunderbird\profile

Thanks for your reply, David.

I've waited for a few days to see if any issues became apparent with the "symlink" procedure I've tried.

So far, there hasn't been any serious issues, but there's one issue that has occurred occasionally that doesn't seem to cause any real damage but it's enough of an annoyance that I'll probably switch to your suggested solution.

What I'm finding is that, since moving my profile using the "symlink" approach, performing an action in Thunderbird (like deleting a message, moving a message, etc.) will occasionally result in Tbird "losing" all the messages in the UI. All the message folders in Tbird's UI suddenly display as completely empty. The first time it happened, I thought it could have been a huge mistake trying the "symlink" idea and I'd corrupted my profile. But I exited TBird, restarted it and discovered that everything was restored in the UI. Even the operation I did (message deletion, move, etc.) when the UI seemed to "lose everything" had been successfully performed. It seems that after the operation the UI doesn't update successfully and creates a scary, but harmless, result.

This has only happened 2 or 3 times over the past few days. And each time it's happened everything was restored in the UI by just closing and restarting Tbird, but it's enough of an annoyance that I'll probably abandon using the symlinks. And since this seems to me to be an indication that using symlinks is somehow causing Tbird to act unstable or "flaky" leaves me concerned that something more consequential could occur in the future. So it's probably not worth it, given the annoyance and the existence of another technique that is regarded as safe.

Thanks again.

I'm glad to assist. And all the official steps do is simplify for many what is really a simple process: - when thunderbird starts, it opens the text file, profiles.ini, at c:\users\<yourid>\appdata\roaming\thunderbird - that little text file has the location of the profile and thunderbird opens it. that's what the profile manager steps update that I listed. - it is also possible to just open that file in Notepad and make the necessary change to point to the profile.

I thought I'd leave this message to ask if there's some issue that can result by doing it as I did.

I don't think so. By using the symlinks nothing changed for Thunderbird, and you did avoid the hassle having to tell Thunderbird about the new location of the profile.

I then copied the two original profile directories into their new respective directories on the D drive:

Typically the data underneath the AppData\Roaming folder is called the 'profile'. It contains all your settings, mail, address book, etc. This is what should be backed up on a regular basis.

The data underneath AppData\Local is primarily cache data, and doesn't need to be backed up. To avoid backing up the cache along with the profile it's deliberately located outside of the profile folder.

I even tried the Thunderbird "backup profile" feature and it created a zip file that seems to contain a subset of the contents of the "Roaming" profile directory, which I suspect is perhaps all that really needs to be saved in a profile backup?

Correct. Just make sure your backup program follows the symlink.

since moving my profile using the "symlink" approach, performing an action in Thunderbird (like deleting a message, moving a message, etc.) will occasionally result in Tbird "losing" all the messages in the UI.

I've seen a similar effect after automatic compacting has been triggered. Not sure what's causing it, but I'm pretty certain it has got nothing to do with your "symlink" approach.

since moving my profile using the "symlink" approach, performing an action in Thunderbird (like deleting a message, moving a message, etc.) will occasionally result in Tbird "losing" all the messages in the UI.

I've seen a similar effect after automatic compacting has been triggered. Not sure what's causing it, but I'm pretty certain it has got nothing to do with your "symlink" approach.

This never happened at all prior to moving the profile to the different drive. That's why I thought that it was moving the profile directories that caused it to occur. It's interesting to hear that you're seen it occur with other installations -- I assume regardless of the whether or not the profile has been moved.

But that may actually be a clue? My C: (system drive where the AppData directory is located) is an M.2 NVMe SSD. The D: drive where I moved the profile files is a SATA spinner with a much slower transfer rate. Just a wild guess, but maybe it could be a race condition in the code when the compacting operation occurs?

One thing I'm going to try before switching to doing the "profile manager" method is to just move back the "profile" directory under AppData\Local -- which apparently wasn't necessary to move in the first place. After that, I'll see if the problem still occurs over the next few days. If that stops the issue, I'm all set.

I think while I'm changing things anyway, I'm going to make one other modification. I should have created the symlink one level higher in the directory tree. Have ...\AppData\Roaming\Thunderbird contain a symlink pointing to a "Profiles" directory in D:\. That way if, in the future, any new profiles are created they'll go into the directory on D. The way I did it up to now, I just moved a specific profile directory to D, but any new ones will get created on C. When I first did this, it was just a quickie thing and I didn't spend a lot of time thinking it through.

If after the changes, I still have the annoyance of the occasional blanking out of the folder contents until I restart Tbird, then I'll just blow away the remaining symlink and try the "profile manager" route.