192.168.1.2 host

My system is picking up 192.168.1.2 host from somewhere. I had changed
our internal IP address to 192.168.15.2 about 3 years ago, but I keep
seeing this in my GWIA screen. Where is GWIA picking up the incorrect
host information from? The hosts file in the ETC directory had the
incorrect information, and I corrected it, however I just noticed the
error still remains. I am strictly using public DNS servers. Any Ideas
where it is pulling the IP address from?

DMN: MSG 1266 Recipient unknown: madline@pmcs-inc.com
03-16-07 01:33:33 0 Queuing deferred message:
PMCS_411/SYS:\GDOMAIN\WPGATE\GWIA\send\s5f9737b.000
03-16-07 01:34:46 6 DMN: MSG 1267 Send Failure: 450 Host down
([192.168.1.2])
03-16-07 01:35:03 0 MSG 1268 Analyzing result file:
PMCS_411/SYS:\GDOMAIN\WPGATE\GWIA\result\r5f9737b.000
03-16-07 01:35:03 0 MSG 1268 Detected error on SMTP command
03-16-07 01:35:03 0 MSG 1268 Command: [192.168.1.2]
03-16-07 01:35:03 0 MSG 1268 Response: 450 Host down ([192.168.1.2])
03-16-07 02:22:03 0 Queuing deferred message:
PMCS_411/SYS:\GDOMAIN\WPGATE\GWIA\send\s5f97ee1.003
03-16-07 02:23:17 6 DMN: MSG 1269 Send Failure: 450 Host down
([192.168.1.2])
03-16-07 02:23:33 0 MSG 1270 Analyzing result file:
PMCS_411/SYS:\GDOMAIN\WPGATE\GWIA\result\r5f97ee1.003
03-16-07 02:23:33 0 MSG 1270 Detected error on SMTP command
03-16-07 02:23:33 0 MSG 1270 Command: [192.168.1.2]
03-16-07 02:23:33 0 MSG 1270 Response: 450 Host down ([192.168.1.2])