Assegnate 5 su 5 stelle

Very useful.

Questa recensione riguarda una versione precedente (4.0.0) del componente aggiuntivo. 

This sounds like a known problem. You can get a fixed version from https://github.com/lieser/dkim_verifier/issues/279#issuecomment-997386893.

Next time please don't use the reviews to report problems. Use https://github.com/lieser/dkim_verifier/issues or write me an E-Mail (in English or German).
See also https://addons.thunderbird.net/en-US/review_guide