Hello
Email sent to a user, for example when you approve or reject his account, are sent using the administrator language in backend. They should be sent using the user preferred language in frontend.
I use English in backend, because French backend translation is far from perfect (and I think that for some languages, there is no backend translation at all

But of course the mails need to be send to my users in their language (French).
Regards
Not fixed (at all) as of ES 1.4.8