[c-nsp] NAT - multiple inside source, single outside address

[Matt Stevens]

I have an issue I'm trying to fix with NAT.

We have a group of SMTP servers, all with their own addresses. Due to 
some customer firewall issues I need all the servers to deliver outbound 
mail using a different address than their own. All other inbound and 
outbound traffic should be untouched.

My first attempt looked something like this:

   ip nat inside source static 10.35.0.11 172.16.2.11 route-map SMTPout
   !
   ip access-list extended cluster11-smtp-out
    permit tcp host 10.35.0.11 neq smtp any eq smtp
    permit tcp host 10.35.0.12 neq smtp any eq smtp
   !
   !
   route-map SMTPout permit 10
    match ip address cluster11-smtp-out

The problem is, when I try to add a second inside source static:
ip nat inside source static 10.35.0.12 172.16.2.11 route-map SMTPout

it's just silently ignored, and doesn't show in the config. I tried 
adding extendable - with the same effect.

Is there a way to do this?
-- 
matt