Hi, I would like to set Email Default language to all recipient. I am aware of the option “Custom email and language for each recipient” on the settings, but that is not what I am looking for.

I do not want to enable it because I need to dynamically set the Email subject and text with the Salesforce Apex Toolkit. If I enable this option, I cannot set the subject and text programmtically.
I want to set the default language to German (Currently in English).

How do I achieve this?