I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG.  These comments were written primarily for the benefit of the security area directors.  Document editors and WG chairs should treat these comments just like any other last call comments.

The draft defines a new IMAP response code for a standard way to represent a progress of long server operations.
The draft is well written and easy to understand. I found no security problems with this draft.