Web vs Mail services

["isplist@xxxxxxxxxxxx" <isplist@xxxxxxxxxxxx>]

I'm using LVS for various web services in load balanced manner and all works
fine.

I've set up a new mail cluster which I'd like to use LVS in front of but for
some reason, am having problems this time around and cannot find the reasons
for this.

The mail services are standard ports 25, 80, 143, 110 for testing. The mail
server/s is/are using NAT IP's behind one real IP for the cluster.
Since they are clustered, I will only note one server from this point on.

So, when checking if everything works externally, when not behind LVS, all
does seem to work just fine. When LVS is in front, nothing seems to work.

Here are some additional details. I've obviously overlooked something;

On the servers, in /etc/sysconfig/iptables;

*nat
:PREROUTING ACCEPT [602:53060]
:POSTROUTING ACCEPT [13:885]
:OUTPUT ACCEPT [13:885]
-A PREROUTING -d 192.168.1.151 -p tcp -m tcp --dport 25 -j REDIRECT --to-ports
25
-A PREROUTING -d 192.168.1.151 -p tcp -m tcp --dport 80 -j REDIRECT --to-ports
80
-A PREROUTING -d 192.168.1.151 -p tcp -m tcp --dport 110 -j REDIRECT
--to-ports 110
-A PREROUTING -d 192.168.1.151 -p tcp -m tcp --dport 143 -j REDIRECT
--to-ports 143
-A PREROUTING -d 192.168.1.151 -p tcp -m tcp --dport 993 -j REDIRECT
--to-ports 993
-A PREROUTING -d 192.168.1.151 -p tcp -m tcp --dport 995 -j REDIRECT
--to-ports 995
COMMIT

On LVS,

serial_no = 114
primary = 192.168.1.76
service = lvs
backup_active = 1
backup = 192.168.1.77
heartbeat = 1
heartbeat_port = 539
keepalive = 6
deadtime = 18
network = direct
nat_nmask = 255.255.255.255
debug_level = NONE
monitor_links = 0
virtual HTTP {
     active = 1
     address = 192.168.1.151 eth0:1
     vip_nmask = 255.255.255.0
     port = 80
     send = "GET / HTTP/1.0\r\n\r\n"
     expect = "HTTP"
     use_regex = 0
     load_monitor = none
     scheduler = wlc
     protocol = tcp
     timeout = 6
     reentry = 15
     quiesce_server = 0
     server qm249 {
         address = 192.168.1.249
         active = 1
         weight = 0
     }
     server qm250 {
         address = 192.168.1.250
         active = 1
         weight = 0
     }
}
virtual POP {
     active = 1
     address = 192.168.1.151 eth0:1
     vip_nmask = 255.255.255.0
     port = 110
     send = "GET / HTTP/1.0\r\n\r\n"
     expect = "HTTP"
     use_regex = 0
     load_monitor = none
     scheduler = wlc
     protocol = tcp
     timeout = 6
     reentry = 15
     quiesce_server = 0
     server qm249 {
         address = 192.168.1.249
         active = 1
         weight = 0
     }
     server qm250 {
         address = 192.168.1.250
         active = 1
         weight = 0
     }
}
virtual IMAP {
     active = 1
     address = 192.168.1.151 eth0:1
     vip_nmask = 255.255.255.0
     port = 143
     send = "GET / HTTP/1.0\r\n\r\n"
     expect = "HTTP"
     use_regex = 0
     load_monitor = none
     scheduler = wlc
     protocol = tcp
     timeout = 6
     reentry = 15
     quiesce_server = 0
     server qm249 {
         address = 192.168.1.249
         active = 1
         weight = 0
     }
     server qm250 {
         address = 192.168.1.250
         active = 1
         weight = 0
     }
}
virtual SMTP {
     active = 1
     address = 192.168.1.151 eth0:1
     vip_nmask = 255.255.255.0
     port = 25
     send = "GET / HTTP/1.0\r\n\r\n"
     expect = "HTTP"
     use_regex = 0
     load_monitor = none
     scheduler = wlc
     protocol = tcp
     timeout = 6
     reentry = 15
     quiesce_server = 0
     server qm249 {
         address = 192.168.1.249
         active = 1
         weight = 0
     }
     server qm250 {
         address = 192.168.1.250
         active = 1
         weight = 0
     }
}