Hi all,
the solution is existing, but it takes to many clicks to change the spelling language of the existing text:
Word - two clicks: one on the language in the status bar and one to select the new language
Outlook - four clicks: Review ->Language ->Set proofing language and one to select the new language
Somebody may think, there's no big difference between two and four clicks, but people having to switch 5-10 times within one mail find it very annoying, especially because there's no keyboard shortcut (known to me).
For typing new text, Windows+Space is a great solution, as I don't have to move my hand from the keyboard to change the language.
@Microsoft: it shouldn't be too difficult to implement the same solution for existing text!!