No email reports

No more email reports are sent and I can’t find any errors. Reports are sent manually. I tried to switch to an email server. Not working. No entries in the error log.
This function works and sends a test email.
There is no entry in the cronjob for sending an email. Where are the cronjobs processed at matomo?

I have been searching for days for the error and I cannot find anything.
Does anybody have an idea?


Matomo version: 3.13.4
MySQL version: 10.1.44-MariaDB-0+deb9u1
PHP version: 7.3.14