Email notifications are sent on every build failure by default for Jenkins. As discussed on the mailing list, if email notifications are only desired on state changes than one should install the email-ext plugin and for each project add still-failing triggers which all notifications unchecked. Unfortunately, the proposed solution does not work and the emails are still sent. Removal of $PROJECT_DEFAULT_RECIPIENTS and $DEFAULT_RECIPIENTS does not fix the issue either. The only solution that seems to fix the problem is to disable notifications altogether, an undesirable solution.