http://tools.ietf.org/html/rfc3501#page-34 defines the following responses:
REQUIRED untagged responses: FLAGS, EXISTS, RECENT
REQUIRED OK untagged responses: UNSEEN, PERMANENTFLAGS, UIDNEXT, UIDVALIDITY
Should return a list of tuples: [ { exists, 17 }, { recent, 2 }, { unseen, 8 }, ...]