Cyrus IMAP and the Ampersand

An interesting thread has occurred on the Cyrus IMAPd mailing list regarding the lowly ampersand. Apparently in the encoding used by IMAP (a "modified UTF-7 encoding") the ampersand ("&") requires escaping. So it works fine to have subfolders whose name contains an ampersand as IMAP clients, of course, use the appropriate IMAP encoding. But if your username (internally the name of your INBOX) contains an ampersand you can run into trouble. this is because when the existence of the INBOX is checked the authentication request isn't necessarily encoded in the same way. So if you use an IMAP server user names should be kept in conformance with the IMAP encoding, or more simply, stick with the GOODCHARS defined in Cyrus' mboxname.c