What triggers an ora-00942 when executing “grant execute on ‘SYS’.UTL_MAIL to public;”

We wanted to configure the mailing on our newly installed database 21c.

-- Instructions

@$ORACLE_HOME/rdbms/admin/utlmail.sql
@$ORACLE_HOME/rdbms/admin/prvtmail.plb

ALTER SYSTEM SET smtp_out_server = ‘smtpout.basf.net:25’ SCOPE=both;

-- ACLs have also been configured

A test mail with the sys user works without any problems.

But when we want to set up the authorization for other users, we get an error:

grant execute on "SYS".UTL_MAIL to public;
ORA-00942: Table or view does not exist

https://docs.oracle.com/error-help/db/ora-00942/00942. 00000 - "table or view%s does not exist"