I've used the PloneMailList implementation in another project. It works well to add 'imap4-utf-7' as codec.

The twisted imap implementation seems to have been updated to properly support non-printable ASCII, but the twisted imap API is problematic for imaplib because twisted seems to expect its arguments to already be Python unicode.

So can we be specific about what kind of API change would satisfy this issue:

1) a number of API methods take one or more mailbox arguments. Of course, imaplib currently expects these to be ASCII, but what kind of argument should the methods take? UTF? Unicode? So would the library need a class property to describe an optional specified input encoding? Would it be expected to take Python unicode?

2) some methods, such as list and lsub, return mailbox names UTF-7 encoded and embedded in larger ASCII strings. Would imaplib be expected to alter the contents of these large strings and transform them into another other encoding (when a switch as described in 1) is active)?