Guessing that you're talking about a client development SDK of some kind
He's using the c-client API in the UW IMAP toolkit. c-client has the capability of converting arbitrary charset text to UTF-8, and of converting UTF-8 into most charsets.
If C and Windows is your target, your interfaces need to be UTF-16 (not UTF-8) since UTF-16 is what a Windows "wide char" is.
It depends upon whether he's going to to use the Windows Unicode routines. UTF-16 is probably more efficient for editing since it's it reduces (but not eliminates) the variable character bit-width problem. Most email will only use characters in the BMP, so UTF-16 degenerates into UCS-2 (no surrogates). However, there's still all the fun and laughter of combining characters...
On the other hand, using UTF-16 adds an additional conversion step.
If developing under Unix, then UTF-8 is the name of the game.
-- Mark --
http://staff.washington.edu/mrc Science does not emerge from voting, party politics, or public debate. Si vis pacem, para bellum.
