Openproject does not send statusmails, testmail works

Hi Openproject Community.
I have the following issue with my openproject app.
In the admin area I have configured a mailserver per smtp. Testmail works fine and will be sent immediatelly.
But no statusmail will be send if a issue has been changed.

I have read abaout a delay_job but in ucs it was not able for me to locate the jobscript.
Can anyone helb me?

Many thanks,