Oracle 12C ACL for smtp2go setup

[admin]

BEGIN
DBMS_NETWORK_ACL_ADMIN.append_host_ace (
host => 'mail.smtp2go.com',
lower_port => 587,
upper_port => 587,
ace => xs$ace_type(privilege_list => xs$name_list('http'),
principal_name => ‘myuser',
principal_type => xs_acl.ptype_db));
END;
/