So I use Cobian Backup v11 (Gravity) to save my folders to an external hard drive. One of the folders is the Thunderbird folder which contains backups of emails and config info to personalise the application. I ran a backup just a week ago (the end of August) After reinstalling Windows 10 and restoring my profile from the backup, I discovered I'm missing emails from April until the end of August (both received and sent). I don't know whether this is an issue with Thunderbird or Cobian Backup. Now the way Cobian Backup should work is that when it does an incremental backup (which I performed), it only saves files that have the archive flag set. The archive flag is set on a file when it has been modified and then as I understand it, Cobian Backup should clear the flag when it backs up a file. Then when new emails arrive or are sent, the composite email files are flagged for archiving again since they have changed. I'm not sure what went wrong here. Any ideas?