Rated 1 out of 5 stars

Experience with ImportExportTools (IET):
E-Mails exported from mail-folders in Mbox-Files.
New Installation of Thunderbird.
Attempt to reimport mails with IET fails with message:
"Reimport to this folder is not possible:
Probably it is a folder of an IMAP-account or a newsgroup".
In fact it is the same folder from which the mails were exported.
Effect of application or IET: Loss of all exported mails!

U
please post any issue in the repository:
https://github.com/thundernest/import-export-tools-ng/issues
I think you need some help understanding the use of the extension. if you exported successfully you have not lost any.

Rated 1 out of 5 stars

ImportExportTools exportiert die Mails in eine Datei ohne Dateierweiterung (File Extension) und Thunderbird ist nicht in der Lage, das exportierte File ohne Dateierweiterung wieder zu importieren. Das Tool ist unbrauchbar und verursacht nur grossen Zeitverschleiss.

U
I think this really is not a review, but rather a question because it appears that you may be referring to exporting mbox files which to not have extensions.
if you could post a question on your use case in the repository I can help you there
Christopher