Question about SMTP Tweak

Hello, when I use "SMTP Restrictions" tweak, it creates 4 rules on my Iptables, like: -A OUTPUT -p tcp -m multiport --dports 25,465,587 -m owner --gid-owner 994 -j ACCEPT -A OUTPUT -p tcp -m multiport --dports 25,465,587 -m owner --gid-owner 12 -j ACCEPT -A OUTPUT -d 127.0.0.1/32 -p tcp -m multiport --dports 25,465,587 -m owner --uid-owner 202 -j ACCEPT -A OUTPUT -p tcp -m multiport --dports 25,465,587 -m owner --uid-owner 0 -j ACCEPT
Searching for this on Google, someone commented "this is not enough, you have to create a REJECT rule after these four rules" and posted: -A OUTPUT -p tcp -m tcp --dport 25 -j REJECT --reject-with icmp-port-unreachable
Makes sense, because INPUT and FORWARD has similar rules. Please, can you confirm if this is true or not necessary? Another point: I had to create manually the rules on my ip6tables file. My server has a IPv6 but it's not active. This is expected or cPanel does not create these rules on IPv6 Iptables file? Thanks, Rogerio