Global property 'Node Offline Email Notification' (in 'Configure System') does not work.

I have selected the checkbox 'Node Offline Email Notification' and entered my username (not full email address, but the first part, since 'Default user e-mail suffix' is set).

This did not work, so I tried also selecting the same checkbox in the configuration page for each node.

This still did not work. It only works if I enter my username individually in each node.