We have configured ASA 5510. We have configure Ethernet 0/0 ( Outside ) connected with ADSL line and Ethernet 0/1 ( Inside ) Local LAN. we have configured NAT and all the traffic is passing through outside interface. Now we have connected ethernet 0/3 ( leasedline ) interface with static public IP. Now we want to allow SMTP traffic to pass through from this interface.
How to configure it if we want our local lan SMTP traffic sending through new leasedline ( Static Public IP ).
Unfortunately you can't configure 2 default routes on ASA, hence you can't configure 2 separate outside interface on an ASA with 2 default routes.
From my understanding you want to allow SMTP to pass out over the leased line from your local SMTP server and NOT the ADSL line. Is this correct?
If this is the case, Jennifer is correct in stating you cannot configure two default routes on the ASA or perform Policy Based Routing. However, if you route your SMTP traffic via an ISP smart host or similar then this CAN be done. This would mean you could configure a static route to send traffic destined for the ISP/Smart Host server over the leased line interface. Something similar to the following -
route outside1 0.0.0.0 0.0.0.0 gateway_ip 1 (Default route for ALL traffic over ADSL)
route outside2 220.127.116.11 255.255.255.255 gateway_ip 1 (Specific static route for SMTP traffic over Leased Line where 18.104.22.168 represents ISP smart host)
You can ONLY perform this method if you route your email through a provider otherwise you are limited.