How to change the language for Mail.App spell checker?

[Mariano Kamp]

Hi,

   I want to use a german keyboard, english language and alternating 
german or english spell checking when writing mails.

   From what I've understood so far I believe that this is not possible. 
The language of spellchecking seems to be tied to the language I've 
chosen for the whole os.

   Is that true?

Cheers,
Mariano