The qtraceaddr Perl script illustrates how qmail decides how to deliver
messages for any addresses given on the command line. If your qmail
installation used non-default values for conf-qmail, conf-break, or the
alias user, you can specify them in the $QMAIL, $QMAILBREAK, and
$QMAILALIAS environment variables. For example:

    # env QMAILBREAK=+ qtraceaddr address@example.org