Email templates and multi-language

Hi there,

I am using email templates to customize the mails sent to my customer by ProjeQtOr. It works perfectly with French, the main language of my ProjeQtOr instance.
I am willing to open my services to English speaking users. 

I am wondering how I am supposed to proceed to define multi-language email templates based on the user main language.
Is there a way to do this ? If so, could you tell me how ?

Thanks a lot.

Regards