Someone using sendio.com told my client that their ip was corrupt. So i ran a DNS check with MXTools and it said serial number was out of range (serial number 22524) . So I started to look for a solution and got more confused. I tried to change the serial number to 2015070111 because it seemed most people thought that was suppose to be the format. That did not seem to work. ATT handles our mx records and I do not know if i need to change something on the server or call ATT to fix .