Very nice! Noté 5 sur 5 étoiles

I tried it and it works for me.
But I have few issues and proposals.
1. When I remove mail from Yandex - it removes it on server too, but for gmail it doesn't work - it tells me, that it isn't on server. Nothing fatal, of course :)
2. I cannot add my Yahoo account although I don't have Java Quick Starter addon. But WEB notifier allows me access Yahoo. It has other problems, but Yahoo it can follow and access.
3. I think, it worth to add the ability to visit the server in a new tab. Although the mail are in Simple Mail tab, sometimes the user want to go to the server. It seems to me it is not difficult to add the link to server in addon options.
Moreover, server access can be fully independent from main service - like bookmark. If the main window will have a bookmark field (like favorits), the user can add here links to servers and even other sites that he offen use with mails.
In such case this addon becames mail master. Even for mail servers that it can not follow (by different reasons) the user will be able visit them etc.
Thank you.

Cette critique est pour une version précédente du module (2.83).