Hmm I've never tried that before, plus I only use the ASDM, but do have access tot he CLI and have basic experience with this.

How would I do this then?

Say 192.168.28.1 and 192.168.28.2 wanted to go outbound via 10.10.10.10 (public IP)?

I do not use the ASDM, not even sure if it is capable to configure something like this in the ASDM, via cli

global (outside) 99 10.10.10.10

access-list email-servers extended permit tcp host 192.168.28.1 any eq smtp

access-list email-servers extended permit tcp host 192.168.28.2 any eq smtp

nat (inside) 99 access-list email-servers

Basically the above instructs the ASA to NAT servers 192.168.28.1 & .2 when they try an access anything out on the internet using smtp and NAT them to external IP 10.10.10.10

HTH>

Thanks,

As one of the email servers has the public IP (10.10.10.10) assigned to it via NAT, can I just do the above method to just the server that needs it?

Also, are there any useful commands that will show me that it is using this new public IP?

Sorry - I am no confused, if you are performing a specific static NAT - you WILL have to change it from a 1:1 to a 1:Many

You cannot just add an internal server, you will have to configure either a static 1:Many NAT based on an access-list or a policy based NAT.

HTH>

OK, wil I have to first remove the current NAT?

Yes you will have to remove the current NAT statements, and clear the NAT xlate table.

Sorry to confuse:

Could I:

Get the 2 email servers send outbound as public IP 10.10.10.10 on smtp

But only nat 10.10.10.10 inbound to one of the email servers on smtp?

No - the ASA will send return traffic back to either server.

So if you have an environment where only 1 email server is receving/delivering email - but both servers are sending email out to the internet, you need to look at your email environment.