To back up or archive Mozilla Thunderbird folders:
- Make sure Mozilla Thunderbird is not running.
- Go to your Mozilla Thunderbird profile directory.
- Open the Mail folder.
- Look for the file named like the Mozilla Thunderbird folder you want to archive in the Local Folders or an account-specific sub-folder (such as pop.gmail.com, for example).
- Make sure you pick the file that has no extension no the identically named file with the .msf extension. (The right file is Archive, for example, not Archive.msf.)
- Highlight the desired file (or files; hold down the Ctrl (Windows) or Command (Mac) key to highlight multiple files).
- Drag and drop the files to the desired archive location (on a removable medium such as a DVD, an external hard drive, a network drive or internet storage, for example).
- Open Mozilla Thunderbird.
- Delete the folders whose corresponding files you have just copied to the archive location.
- Drag and drop the folders to the Trash folder.
- Click OK.
- Select File | Empty Trash from the menu.
To open a folder you have archived:
- Make sure Mozilla Thunderbird is not running.
- Open your Mozilla Thunderbird profile directory.
- Go to the Mail folder.
- Drag and drop the archived folder file (Archive, for example) from its remote location to the Local Foldersfolder.
- Make sure you do not overwrite existing files.
- If a file with the same name already exists under Local Folders, rename the archived folder file before copying.
- Open Mozilla Thunderbird.
- The archived folder should appear under Local Folders in the folder list.