Review for ImportExportTools by Plons
Rated 5 out of 5 stars
It does exactly what I need: from time to time I want to archive email-messages to cleanup the workingPC.
I save the messagefolders in 2 formats: in EML format: that allows me to put an archive back. And I also save it it HTML, for convenience. The author creates a folder and an file Index.html. Now, THAT is nice !
To create your own collections, you must have a Mozilla Add-ons account.