NC calender reminder automatically mails to all participants

Dear all,

I have not found a solution for this problem, which is already addressed in other postings …
I would like to use appointment reminders to be sent automatically to participants from NC calendar entries. So far they do not.

I have made the SMTP email settings in NC. The test mail arrives succesfully.
When I create or change a calendar entry, an email is sent succesfully.
But a reminder is not sent.

I have set the reminder to e.g. 15 minutes before the start of the appointment and “e-mail”.

But no e-mail is sent. What could be the reason for this?

(Nextcloud, current version
Hoster Allinkl)

Thank you very much!

P.S. This is copy of a German entry by myself on which nobody reacts so far …

How often do you run the cronjob? It must be run more often than these 15 minutes. Or you test to send a reminder 2h before and check if this is working.
You can also check the logs, if you see failed mail sending attempts.