The eMail Integrity CompanyFrequently Asked Questions

When checking the Message History you may see the following event detail: 

On Fri Jan 07 at 09:03 EST, CNAME lookup failed temporarily. (#4.4.3)

As DNS records have grown in size they are beginning to exceed the 512 bytes size limitation of UDP packets. In these situations DNS must switch over to TCP to receive the full answer. Many firewalls, however, are restricted to only allowing outbound UDP packets for DNS lookups causing the "CNAME lookup failed temporarily" error. In order to resolve this issue you will need to change your firewall rules to allow outbound DNS lookups (port 53) to utilize both UDP and TCP packets.