IMAP QRESYNC Extension
charter-ietf-qresync-01

The Internet Message Access Protocol (IMAP), defined in RFC 3501,
specifies a protocol for accessing email messages on a server that
implements a message store from a client. It also includes commands for
manipulating the message store -- creating, deleting, and renaming
mailboxes, adding a message to a mailbox, and copying messages from one
mailbox to another.

Base IMAP as described in RFC 3501 requires that in order to discover
flag changes and expunged messages in a mailbox, the client has to fetch
flags for all messages it knows in the mailbox and compare returned
results with its own state.

This can generate a significant amount of traffic for big mailboxes. The
IMAP CONDSTORE extension (RFC 4551) provides a facility for IMAP clients
to quickly resynchronize mailbox flag changes in a mailbox. The IMAP
QRESYNC extension (RFC 5162) extends CONDSTORE to also cover expunged
messages, and reduces the number of round trips needed to resynchronize
by extending the SELECT/EXAMINE command.

The CONDSTORE and QRESYNC extensions are deployed in both clients and
servers. These deployments have exposed errors and clarity issues in
the specifications, and they need correcting. The IMAP QRESYNC
Extension working group has the task of updating CONDSTORE and QRESYNC
extensions on the Standards Track.

The working group might produce one (combined) or two separate documents
(as now) updating these extensions. The working group will review errata
and update the documents as needed to incorporate those, and will
correct significant errors and inconsistencies, but will keep changes at
this stage to a minimum and avoid incompatible changes.

No other IMAP extension work is in scope for this working group.