Ho un firewall con Centos, uso iptables, squid e dansguardian; ma ho un traffico eccessivo verso indirizzo ip sulla porta smtp, ecco l'output si tcpick

55 ESTABLISHED 118.168.139.116:ivecon-port > 159.213.91.52:webcache
61 SYN-SENT 118.168.194.63:iad2 > 159.213.91.52:webcache
61 SYN-RECEIVED 118.168.194.63:iad2 > 159.213.91.52:webcache
62 SYN-SENT 159.213.91.52:35106 > 91.192.55.191:smtp
53 FIN-WAIT-1 159.213.91.52:38306 > 87.245.192.35:http
53 TIME-WAIT 159.213.91.52:38306 > 87.245.192.35:http
62 SYN-RECEIVED 159.213.91.52:35106 > 91.192.55.191:smtp
62 ESTABLISHED 159.213.91.52:35106 > 91.192.55.191:smtp
63 SYN-SENT 159.213.91.52:42829 > 168.95.6.185:smtp
53 CLOSED 159.213.91.52:38306 > 87.245.192.35:http
56 FIN-WAIT-1 159.213.91.52:42331 > 74.6.140.31:smtp
56 TIME-WAIT 159.213.91.52:42331 > 74.6.140.31:smtp
50 FIN-WAIT-1 220.136.107.235:bpcp-poll > 159.213.91.52:webcache
60 SYN-RECEIVED 159.213.91.52:38305 > 68.71.215.140:smtp
60 ESTABLISHED 159.213.91.52:38305 > 68.71.215.140:smtp
64 SYN-SENT 159.213.91.52:52867 > 168.95.4.215:smtp

sbaglio io, o c'è qualcosa che non va ???