[BlueOnyx:13798] ip address assignment

[wcstaff at webcoast.com]

When I initially set up the server, I used one of my static ip addresses,
ending in 53. Then When I shutdown the old server and brought this one up, I
setup 2 NICS with ip addresses, ending in 51 and 52. 
Initially my server showed that 51 and 53, and 52 and 53 were assigned
together. How do I separate these ip addresses. 
I was looking at my port log and noticed this:
tcp        xxx.xxx.xxx.51:53    
tcp        xxx.xxx.xxx.52:53
Could this be the reason why adding a 3rd NIC and assigning it
xxx.xxx.xxx.53, causes my email to stop?
Thanks in advance
Tom