pfqueue is an effort to give postqueue/mailq/postsuper a console
(ncurses) interface: it won't add any particular functionality to
those provided with postfix itself, but will hopefully make them to
use.

It's a real-time queue scanner, that show per-queue lists of existing
messages; the messages can be deleted, put on hold or released

Just for example, it may be useful to inspect a traffic jam at a given
time, to see what is falling into and unexpectedly crowding you deferred
queue