ASA 5510 NAT issue?

[jerrybolack]

                   We have just added an ASA5510, and now are having some email rejected by customers.  Here is what I have found, and I am looking for recommendations on how to fix.  The vendor that installed doesnt appear to want to help - forgive my ignorance if I say something stupid here, I'm learning this as I go.

outside interface configured as .29 (we have 3 ouside IP's)

MX record points to .28

NAT rule set up to run smtp through .28

Incoming mail works fine, however outgoing mail is going out of .28 not .29.  Some customers to reverse lookups and what not for spam filtering, that is catching our mail coming out of .29 and saying it cannot find our IP (IP doesnt match).  I changed the address on the outside interface to .29, evidently that was a bad idea - nothing worked after that so I had to put it back.

Exact error as seen on our barracuda: 554.5.7.1 Client host has reject: cannot find your hostname xxx.xxx.xxx.28

Any help greatly appreciated!

[Jennifer Halim]

Sorry, a little confused with the IP stated on your post.

If you setup NAT rule for .28, then inbound and outbound mail will be using .28.

But are you saying that outbound mail uses .29 instead?

[jerrybolack]

Yes that is correct.  The NAT rule shows .28 (the correct address).  However servers receiving our mail show it is actually coming out of .29 (the address tied to the outside interface)

[Jennifer Halim]

did you "clear xlate" after you configure the static PAT rule?

if you haven't, try to "clear xlate" and it should be using the new static PAT rule that you configure.

[jerrybolack]

I just did, no luck.  Still the same rejection message.

[Jennifer Halim]

Can you pls try to run packet tracer on the ASA for the outbound SMTP and see whether it is correctly or incorrectly PATing it to .28, and pls kindly share the output of the packet tracer as well.

[jerrybolack]

Everything passes in packet tracer.

Results under NAT:

Type-NAT | Action - ALLOW | Show rule in NAT Rule table

Config

nat (inside,outside) source static Email obj_xxx.xxx.xxx.29 service smtpobj smtpobj

Info

Static translate 192.xxx.xxx.xxx to xxx.xxx.xxx.29