You don't mention what application you are using. Sometimes the language
settings there could give you grief. I just upgraded to 11.10 and when I ran
Reconq browser on Kubuntu for the first time and it was in Spanish, menus
and all. I checked KDE and it had my settings as Canadian English. So I
looked at the Spanish Rekonq settings and found it was Catalan. The
shortform for both is CA. I could not find anything that made sense because
I do not speak Catalan. So from the list of languages I saw something that
might be English but turned to be some unreadable script however I saw Elmer
Fudd in English in the list. I changed the settings and now saw Engwish in
the list. I changed to that and now all is fine.

So check the application settings in the receiving client. Also check
character encoding and font selection. I am not sure what they would be in
your case.

Ubuntu works differently from KDE in that it has no universal control panel
and locations settings have changed with Unity. I don't use a keyboard
changer so there may be some simpler explanation.

But it is nice that some KDE developer has a sense of humor and included
Elmer Fudd otherwise I might still be in some unreadable Asian script.

You may need to install fonts for the language in question.

The recipient of question marks instead of letters has to encode his email
program correctly. In Thunderbird one goes to "options" and then "character
encoder". From the encoder there are choices to be made. Each email program has
an encoder. This will work if the chosen language is installed in the OS being
used. One can play around with various encoders until the correct one is chosen.