Well according to the iptables man page
it says the multiport module will allow you to use --destination-port port[,port], etc. So it looks like it shouldn't be plural (port, not ports) and you also need the multiport module for netfilter.
You could also write it in a for loop, if you wanted
for port in 5631 5633 5635 ; do $IPT -I TRAFFIC -p tcp --dport $port -s 0.0.0.0 -j ACCEPT ; done ; unset port