Problema con Servidor de Mail...

[Archivitos.com]

Bueno los del soporte tecnico me dijeron que es un problema con el firewall del servidor y que tiene que ver algo de los iptables... investigando algo aprendi. ahora me pregunto si alguien me puede asesorar algo mas... les paso algunos datos:

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain INPUT (policy ACCEPT)
target prot opt source destination
acctboth all -- anywhere anywhere

Chain OUTPUT (policy ACCEPT)
target prot opt source destination
acctboth all -- anywhere anywhere

Chain acctboth (2 references)
target prot opt source destination
tcp -- ip1.miserver.com anywhere tcp dpt:http
tcp -- anywhere ip1.miserver.com tcp spt:http
tcp -- ip1.miserver.com anywhere tcp dpt:smtp
tcp -- anywhere ip1.miserver.com tcp spt:smtp
tcp -- ip1.miserver.com anywhere tcp dpt:pop3
tcp -- anywhere ip1.miserver.com tcp spt:pop3
icmp -- ip1.miserver.com anywhere
icmp -- anywhere ip1.miserver.com
tcp -- ip1.miserver.com anywhere
tcp -- anywhere ip1.miserver.com
udp -- ip1.miserver.com anywhere
udp -- anywhere ip1.miserver.com
all -- ip1.miserver.com anywhere
all -- anywhere ip1.miserver.com
tcp -- ip2.miserver.com anywhere tcp dpt:http
tcp -- anywhere ip2.miserver.com tcp spt:http
tcp -- ip2.miserver.com anywhere tcp dpt:smtp
tcp -- anywhere ip2.miserver.com tcp spt:smtp
tcp -- ip2.miserver.com anywhere tcp dpt:pop3
tcp -- anywhere ip2.miserver.com tcp spt:pop3
icmp -- ip2.miserver.com anywhere
icmp -- anywhere ip2.miserver.com
tcp -- ip2.miserver.com anywhere
tcp -- anywhere ip2.miserver.com
udp -- ip2.miserver.com anywhere
udp -- anywhere ip2.miserver.com
all -- ip2.miserver.com anywhere
all -- anywhere ip2.miserver.com
tcp -- ip3.miserver.com anywhere tcp dpt:http
tcp -- anywhere ip3.miserver.com tcp spt:http
tcp -- ip3.miserver.com anywhere tcp dpt:smtp
tcp -- anywhere ip3.miserver.com tcp spt:smtp
tcp -- ip3.miserver.com anywhere tcp dpt:pop3
tcp -- anywhere ip3.miserver.com tcp spt:pop3
icmp -- ip3.miserver.com anywhere
icmp -- anywhere ip3.miserver.com
tcp -- ip3.miserver.com anywhere
tcp -- anywhere ip3.miserver.com
udp -- ip3.miserver.com anywhere
udp -- anywhere ip3.miserver.com
all -- ip3.miserver.com anywhere
all -- anywhere ip3.miserver.com
all -- anywhere anywhere

¿alguna sugerencia de porque me rebotan los mails que mando?
saludos y gracias.