Hi there, after testing it with success with the @admin group, i tried to send a kinda newsletter to @trust_level_0.
It turned out, that nothing is sent after ~6hours.
There is no note about that in the admin panel nor i was able to find something in the server log.
I have discourse v1.7.0.beta6 +1 running.
did you check the group setting for trust_level_0 to enable yourself to mention the group? The default is nobody. 
This setting will impact notifications:
max users notified per group mention
Maximum number of users that may receive a notification if a group is mentioned (if threshold is met no notifications will be raised)
Wonderful, that worked, woohoo 
Thank you!
