Sometimes emails get lost, maybe because another device/program deleted them from the IMAP account, maybe due to removing them somewhere one does not find them anymore. Unfortunately, IMAP is quite poor on tracking such issues. Having the option to enable an incremental backup for a folder would highly improve reliability. This might look like the "earlier file versions" feature in Explorer on network drives that support versioning. If you click on a specific date, a new tab opens to show you the files (or in that case: emails) that were in the folder at that time. And one could simply drag them to a live folder from there. It is probably sufficient to store such backups in the local storage/profile, as this would primarily be a backup for the online IMAP storage. However, one may consider some connection to Duplicati which would allow for nearly endless backup endpoints.
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