Thunderbird must not be running whilst doing anything in the Profile folders.

The file global-messages-db can be deleted. Thunderbird will create a new one. When you perform a search it will be repopulated with data. More info:

• https://support.mozilla.org/en-US/kb/rebuilding-global-database

When you have restarted Thunderbird, make sure you compact all folders first to remove all traces of hidden 'marked as deleted' emails.

Thank you. That substantially reduced the Roam profile size that has all of the mail boxes in it. I have compacted and eliminated 'global-messages' -- but the Profile called 'Local' in Thunderbird remains at 105 Mb -- how can I reduce the size of that? Thanks!

re: the Profile called 'Local' in Thunderbird remains at 105 Mb

A Profile is something either auto created when you first ran Thunderbird or a profile you created via Profile Manager? Typically Thunderbird Profile names are like this xxxxxxxx.default, where the x's are letters and numbers. Unless you created it and gave it a name. A profile contains all your mail accounts, emails, address books and preferences, plus a bunch of files including eg: global-messages-db So I'm not sure you actually mean a 'Profile' called 'Local'.

Do you mean: The special default mail account called 'Local Folders'?

Or are you refering to the 'Appdata' 'Local' folder file ? eg: C:\Users\Windows user name\AppData\Local\Thunderbird\Profiles\profile name

Windows uses the Appdata\Local folders for application data that does not roam with the user.

Thunderbird must be closed before doing anything in these files and folders.

In the Local\Thunderbird\Profiles\profile name, there should be a load of cache files. If you delete those cache files, when you start up Thunderbird, Windows will auto create more cache files.

I tested this by creating a folder on desktop called 'Local TB prof cache' and then moving the contents of the Local\Thunderbird\Profiles\profile name to that folder. I did not delete, move or copy the profile folder name, just it's contents. so the profile name folder was empty. I suggest you perform the same test.

I did discover an old profile name which I had deleted a long time ago from 'Roaming', but forgot to remove it from 'Local', so I deleted it whilst I was in that folder.

Then restarted Thunderbird and a load of new current cache files appeared. i tested Thunderbird and it is working perfectly ok. So I deleted the copies stored in folder I created on desktop called 'Local TB prof cache'.

There is also the method using:

• Tools > Clear Recent History.

Much thanks for both!! Really helpful.