Summary emails, new users and SSO

It helped a little bit but did not solve the issue. To test things I set the Summary email frequency to 30 minutes and the maximum notifications per day to 1. I set the last seen setting to 365000. Basically users added to Discourse within the last 17 days received emails and a few users that have been seen recently but had been created earlier also received emails. I can confirm that all users are activated -or at least I can from a random selection of users that did not receive emails. Not sure how to fix this. Is there anything I can reset manually?