Help! How to change Outlook default language?

[Ventilaator]

Hello,



I have three input languages installed on my computer: English (default), Estonian and Russian.
Now when composing an email, I for example need to write in Estonian (UTF-8 encoding for special characters for example), I change the language at the Windows language bar to Estonian.
The problem is that although Estonian language works fine when writing to message body, whenever mailto or title textboxes get focused, the system language is automatically converted back to English.
Tried setting system default language to Estonian, but when writing to message title or mailto, it still changes to English, which means I am unable to write characters like õäöü.

How to fix this problem?

Thanks in advance,
Vent