i have 2930 set ip on 2 bt 2wire adsl routers.
been running for about 6mths initially i had to limit 1 computer only to use wan1 which i eventually figured out. All has been fine.
We now have decided to move to 1and1 mailxchange for email service and have major problem. 1and1 do a ip check so mailxchange wont work.. have checked with them and there microsoft exchange is the same.
So how do i force users computers to only use either wan1 or wan2 for imap mail. and do normal balanceing at all other times.

Set a load balancing rule that includes the IMAP port number and your entire IP address range - for example:

Protocol: TCP
WAN: WAN1
Src IP Start: 192.168.1.2
Src IP End: 192.168.1.254
Dest IP Start:
Dest IP End:
Dest Port Start: 143
Dest Port End: 143

We have done this for https (port 443) otherwise some banking and forum sites get confused.