ssl_cert: Can't open file permission denied

Dovecot 2.3.3 (dcead646b) openSUSE Leap 15.0

I am getting a weird error message:

Fatal: Error in configuration file /etc/dovecot/local.conf line 16: ssl_cert: Can't open file /etc/foobar/ssl/certbot.pem: Permission denied

I have tried the following:

• chmod -R 655 /etc/foobar/ssl (/etc/foobar is 755)
• create "ssl_users" group add dovecot to it chown -R dovecot:ssl_users /etc/foobar/ssl

How can I fix this ? There's no obvious solution ?