Somehow I totally forgot to follow up on this.
The email forwarder we are using is from Mady MTA service, it sits on any PC in the domain.
www.ocloudsoft.com On our 5312 IP Phones, I have setup the following.
MAC ADDRESS:
PHONE IP ADDRESS: 0.0.0.0
DEFAULT GATEWAY IP: 0.0.0.0
SUBNET MASK: 0.0.0.0
CUR CONTROLLER IP: EXTERNAL PUBLIC IP
ICP1 IP ADDRESS: EXTERNAL PUBLIC IP
ICP2 IP ADDRESS: 0.0.0.0
ICP3 IP ADDRESS: 0.0.0.0
ICP4 IP ADDRESS: 0.0.0.0
TFTP SVR IP ADDRESS: EXTERNAL PUBLIC IP
VLAN ID: None
L2 PRIORITY: None
DSCP: None
IPA IP ADDRESS: ICP PRIVATE IP
DNS1 IP ADDRESS: 0.0.0.0
DNS2 IP ADDRESS: 0.0.0.0
I have our system on VLAN 99, and such the phones look to the DHCP server for help.