How can I change the charset encoding of outgoing E-mail messages?

It is possible to send E-mail messages in HTML, plain text (MIME encoding) and plain text (no MIME encoding).

In all three cases, the charset encoding being used is UTF-8.
There are some countries, where UTF-8 is not in wide use, and 9210 users need the ability to switch to a different encoding to make it easier for their correspondents to receive E-mail messages from them.

How can this be accomplished?

NOTE: this is not a question about E-mail messages arriving at the Nokia 9210. We don't have problems with them, once we use the right character set converters.