What is the exact path to the cache and cache.trash### folders?

O:\email\profile name\Cache.Trash899 O:\email\profile name\Cache

etc.

That isn't the default profile location. Did you move your profile to O:\email ?

In any case, you can safely delete the cache.Trash### folders while Thunderbird is closed. Why they have been created in the first place I don't know.

Wrt the 'Cache' folder, it doesn't make sense to delete it, as it will be re-created the next time Thunderbird starts. However, normally 'Cache' should not be located in the profile itself, but underneath C:\Users\<user_name>\AppData\Local\Thunderbird\Profiles\<profile_name>

Do you see a 'Cache' folder underneath that path?

So is it a network drive, a share, a cloud location like drop box or what?

Drive O Sounds like it might well be a USB key drive.or even https://www.odrive.com/

People ask these reasonable sounding questions, but leave out the important bits, like why their installation might be producing files no one else has.

Yes, I store all of our Thunderbird profiles on a NAS device so that they can be accessed from any of our computers. I have mapped the applicable directory to O: drive.

Does this cause the creation of extraneous cache folders? Are the cache.trash### folders associated with searching the trash folder for deleted emails?

I do not have any profiles in the default location on %appdata%. There is no cache folder on %appdata%\Thunderbird.

I deleted all of the cache and cache.trash### folders, reducing my profile size dramatically. The cache folder was recreated, but substantially smaller in size as well. All working properly.

Thanks for the help.

Does this cause the creation of extraneous cache folders? Are the cache.trash### folders associated with searching the trash folder for deleted emails?

I don't know. But accessing the same profile from multiple clients is certainly problematic.

There is no cache folder on %appdata%\Thunderbird.

As said before, there normally is a Cache folder. So you did something, that prevented it from being created there. It's possibly related to moving the profile, but I'm guessing here.

All working properly.

When your problem is fixed, can you mark the topic as 'Solved' please? Thank you.

I'm a bit confused.

TB support articles indicate that profiles can be stored on a NAS for access from various computers on the network. There is a warning that all computers should be using the same OS (i.e. Windows, Linux, Mac OS, etc). All of my computers are running various versions of Windows.

The cache folder is noted as a folder in a profile and instructions for moving a profile do not mention that the cache folder should not be copied to the new profile location.

Not sure what I did wrong to cause the cache folder problems, but I followed the suggested method for moving a profile.

Thanks again for your help

TB support articles indicate that profiles can be stored on a NAS for access from various computers on the network.

Do you have a link?

The cache folder is noted as a folder in a profile and instructions for moving a profile do not mention that the cache folder should not be copied to the new profile location.

I may have had the same effect when I moved the profile to a different drive, but I don't remember it exactly. Setting this pref would move it to the desired path. browser.cache.disk.parent_directory <path>

http://techgage.com/article/sharing_your_thunderbird_profiles_between_pcs_and_oses/

http://www.makeuseof.com/tag/3-ways-to-sync-thunderbird-emails-across-multiple-computers/

These aren't Thunderbird support articles. Just because someone writes these articles doesn't mean that it is a good idea to do so.

I'd hope you didn't miss the disclaimer from your first link: "Just be aware that you will not be able to access the same profile simultaniously from different clients, but it will mean that all clients will be synchronised to the same data."