Binary package “pmailq” in ubuntu xenial
postfix mail queue manager
pmailq parses the output of command from postfix (postqueue -p). It permits
to perform some actions on a group of entries in queue (like removing or
displaying them in a machine readable format). They are selected by applying
filters (wildcards are allowed) on criterias like email address, error message
from SMTP server, message size, mail status in queue.