I use Mozbackup. Ineed to import two seperate sets of emails
I have used Thunderbird 32bit for years, and made Mozbackups every Friday. I recently found Thunderbird 64bit. I shut down my 32 bit and renamed the icon so I knew it from the new 64 bit icon. I copied the 32bit profiles to a separate folder. After installing the TB64 bit versions it asked me to setup a new Profile. I followed the path to the location of the default profile in the TB64 bit and, to my surprise i saw a Default and a Default-release. Not knowing if either would work I used Mozbackup to restore my profile i had made before I shut down the TB 32bit. I started the TB 64bit and hey presto it all seemed to work. If I now try and copy other Mozbackups (mail Only) into my current Profile it overwrites my current emails.....I appear to have lost about 4 days worth of emails. I have tried various cominations of using the old Mozbackup 1st and then the last Mozbackup i did and the same occured these 4 days of file seem to have vanished, is this a problem in overwriting or something else. Should I even try and recovery emails like this.
- User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:73.0) Gecko/20100101 Firefox/73.0
Lets start at the beginning. Mozbackup is old, unmaintained and not really up to the job as it once was. Start by getting a new backup solution. Even the author of mozbackup posts on his site saying you use it at your own risk.
If nothing else works for you the import export tools addon has a backup option. https://addons.thunderbird.net/en-US/thunderbird/addon/importexporttools-ng/?src=ss
Although I would recommend something faster. Perhaps this will assist https://www.pcworld.com/article/3201971/best-windows-backup-software.html
All you need is something that backs up your profile location which you can determine by going into the troubleshooting information on the help menu and selecting the show profile button. Note however that Thunderbird needs to be closed when a backup occurs or the backup will almost certainly be incomplete.
Opening the windows run dialog (windowskey+R) and typing %appdata%\Thunderbird will arrive at the top level folder where Thunderbird stores it's data. I would recommend backing up that folder and everything below it, not just your profile folder as mozbackup does.
Note that Thunderbird 68 starts a profile per install arrangement and going back Thunderbird versions becomes more difficult, the program not wanting to use profiles used with higher versions. Backwards comparability will not be enforced going forward so irrevocable changes to profile information may occur on update in the future.
There is no practical difference in the 32 and 64 bit versions as they stand, only in how they interact with the operating system however removing profile folders has become a somewhat more complex thing as you will now have a release folder created by the profile per install. The profile in use should not change, but for a significant number of folks it does. https://thunderbirdtweaks.blogspot.com/2019/09/i-lost-my-profilemail-on-update-to.html