The help for mailman qfile refers to non-existent bin/dumpdb
mailman qfile --help
says in part
-p, --print / -n, --no-print Don't attempt to pretty print the object.
This is useful if there is some problem with
the object and you just want to get an
unpickled representation. Useful with
'bin/dumpdb -i <file>'. In that case, the
list of unpickled objects will be left in a
variable called 'm'.
bin/dumpdb -i <file>
should be mailman qfile -i <file>
.