NOTIFY_FAXMASTER=errors|"errors"|error does not seem to work

I made a fresh install of hylafax 6.0.6-5 with iaxmodem 1.2.0 on ubuntu
14.04.

As mentioned in http://www.hylafax.org/man/current/notify.1m.html I created
a file /etc/hylafax/FaxNotify with

RETURNFILETYPE=pdf
TEMPLATE=de
NOTIFY_FAXMASTER=errors

But even if no error occur ("Notification of facsimile (...): done) the
faxmaster _always_ gets a notfication email. I also tried

NOTIFY_FAXMASTER=error
and
NOTIFY_FAXMASTER="error"
and
NOTIFY_FAXMASTER="errors"

but the faxmaster keeps getting e-mails.

Can somebody give me a hint?