Exchange 2010 not sending mail bounce-backs

Just migrated a customer's email from Exchange 2003 to 2010. The customer is now complaining that they're not receiving bounce messages when they send to bad email addresses. Any thoughts as to how to fix this?

FYI, the 2003 server is still, temporarily, in the mix. But there are no accounts there anymore. It's basically just holding the connector roles.

Also note that from there, mail passes through a SonicWALL ESA3300.
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SeanConnect With a Mentor System EngineerCommented:
Does the SonicWall have mail filtering enabled? If it does i would make sure its not blocking those bounce backs.
Mohammed HamadaSenior IT ConsultantCommented:
It might be a return-path problem in your Exchange transport rule.

Could you test exchange and see if you get any messages here?
d0ughb0yAuthor Commented:
Lots of tests. Which test did you want to see? I did the inbound SMTP mail flow test, which passed with one warning: The test passed with some warnings encountered.
The Additional Details were: Unable to determine SMTP capabilities. Reason: Authentication failed to the SMTP server. Elapsed time: 1012 ms

Was there something else?
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Mohammed HamadaSenior IT ConsultantCommented:
The test's purpose to see if it'll come with any errors, but this warning doesn't tell much.
can you check the return path in your transport rule please? could you post a screenshot
Blue Street TechLast KnightsCommented:
Hi d0ughb0y,

Perform a packet capture and test from one of the users sending to a known erroneous email account.

In Exchange, what does Message Tracking yield? Is this occurring in OWA as well? To test a user in OWA, again by sending to a known erroneous email account, take Outlook Offline and make sure EAS is disabled temporarily so that the problem doesn't replicate through other sources. This methods allows for direct troubleshooting of Exchange.

Let me know how it goes!
Did you try message tracking ? What that is showing. .

Try to send message through telnet if you see any error.
d0ughb0yAuthor Commented:
The problem turned out to be the SonicWALL. It had been replaced about a month prior to the Exchange migration, and the issue may just not have been noticed. The fix, however, required a SonicWALL Support Engineer to actually SSH into the box, and change the mta config file, setting a specific mail route for the domain, to the internal Exchange server. Thanks for pointing me in the right direction.
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