I suggest you ask the backup and sync people. This is not an issue with Thunderbird but an issue with their implementation. Nothing we can do here except tell you not to use backup and sync as it obviously breaks things.

Thanks for the reply :)

I've had the issue posted on the Google help forums, but no response :(

I posted it elsewhere and got this suggestion:

"Alternative approach: don't add your Thunderbird folder to Crashplan/Google Backup. Instead run a scheduled task that will copy your Thunderbird folder to a new location, and back that up instead. That way it will only sync to the cloud as often as the scheduled task runs (could be weekly, daily, or hourly, depending on your requirements). The downside is that you'll need twice the space on your local machine."

to which I replied:

"Thanks a lot for the suggestion! I think that might be a good option alright! I wouldn't have a clue where to start with setting something like that up though

Say if I did that though, and if my Thunderbird folder is 15gb say, would the new location always be the same size as the Thunderbird folder, so it would replace, rather than just adding an extra 15GB folder each time?

I actually use IMAP via GMAIL for all my accounts, so I wouldn't need such frequent backups, once a day would be more than enough, but it might also be handy to have an older backup too, as it's happened to me before where there's been a problem and I didn't notice it for a few days and I would have liked to have been able to revert to a backup that wasn't the most recent one.

So maybe a scheduled task, one folder that's updated daily and another that's updated weekly? What happens if the computer is off at the scheduled time? Does it just do it the next time it's turned on?"

So hopefully I can find out how to achieve this.

I'm guessing it's all down to the frequency that the thunderbird files are changing that has backup programs having trouble dealing with them?

I think the issue you need to consider is any backup taken while Thunderbird is running will probably not restore without issues.

I use Windows backup to do my backups. You could as well. Where you store those backups is up to you. But the cloud is not my preferred option. The speed of upload to the internet on domestic internet connections is usually very very slow (about a quarter of that advertised as your connection speed.) I would look to local physical media such as a USB hard disk. (I use two 100gb Seagate ones) Swap it out to your gym locker, work desk draw or similar each week so you maintain the offsite backup that the cloud would give. No muss no fuss and exceedingly low tech so very little to go wrong.

I am not going to try and teach you how to write scripts for windows, but the following saved into a file called backup.bat will copy your Thunderbird profile folders when executed

xcopy %appdata%\Thunderbird\*.* /s D:

Where D: is the drive letter the copy will be made to.

See https://www.computerhope.com/xcopyhlp.htm

Hi there, Thanks again for the help on this! Crashplan which I use, also has the ability to backup to an external drive, so I do this too :) So I actually have the following backups of Thunderbird:

1) Crashplan (cloud) 2) Crashplan local (External HDD) 3) Google Backup and Sync (cloud) 4) Gmail

With #4 being how I've set up all my emails now to be managed by Gmail, and then set these up via IMAP with Thunderbird.

So I'm covered pretty well. It's just the annoyance of Backup and Sync by Google trying to deal with the constantly changing files, so I'll look into that script thing to see if that can help :)

Thanks again for your time!