Local Folders are folders that eM Client doesn’t synchronize with the server, meaning their content is stored locally in the application’s database. There are various reasons why you might want to store emails in Local Folders.

For example, you can move or copy your emails there to make space on the server or to secure them in the event of a server failure. You can also move messages there so you can access them while offline. Just don’t forget that you can also use the ‘Download messages for offline use’ function that downloads the content of selected IMAP folders or of the whole account into the application’s local database.

These folders can be enabled/disabled in Menu > Settings > General > General via the 'Show Local Folders' option. The Local Folders will be shown in the left-side folder list under your other account folders.