Recently my firewall started crashing due to being overloaded with traffic. It appears that zimbra is spamming DNS requests at an alarming rate (it is accounting for about 95% of my outbound traffic!). I removed all of the zmMtaRestrictions except zimbraMtaRestriction: reject_non_fqdn_sender to see if that would fix it. Still spamming pretty heavily. Any ideas on what to look into as far as what is causing this?