I was always wondering, why folders on an Exchange server, containing special
characters in the name, show up that different in the IMAP protocol (e.g. using
Mail::IMAPClient in Perl scripts).
But now I understand, this is just the result of the IMAP specification, that uses a modified UTF-7 encoding for non-ASCII characters (see RFC 2060, section 5.1.3).
If you ever need to automatically convert folder names into that modified
UTF-7, the Perl module
Encode::IMAPUTF7 may render useful.
The German Umlauts are encoded in the following way: