Exchange 2010 Send Problem

I have a new 2010 Exchange CAS/Hub Transport Server in a mixed 2003-2010 environment. The CAS/Hub Transport is configured with an internal IP address and also has a Public MIP associated with it. I can receive mail but I cannot send outbound. When I send an outbound, for example, to an incorrect ymail account Yahoo will respond back that it is an incorrect address. So it does appear that my email is getting out.
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mattconroyAsked:
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JdtuckCommented:
Can you send internally?  Can you send a test to one of your personal accounts to see if you receive it?
mattconroyAuthor Commented:
Yes, I can send and receive for internal mail on and between the 2003 and 2010 environments.
JdtuckCommented:
OK, you know you can send to a bad external email account and get a bouceback, but what happens if you send to a good yahoo, gmail, aol, etc, etc.  Does it get delivered or does it give an instant bounceback?
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mattconroyAuthor Commented:
Nothing, the email never gets there and I don't get any bounceback.
JdtuckCommented:
mattconroyAuthor Commented:
I have read that. My send connector is setup as follows:
Address Space: Type is SMTP and Address is ymail.com and Cost is 1
Network: Use DNS (MX) records is checked and Use External DNS Lookup is checked
Source Server: CAS/Hub Transport Server
JdtuckCommented:
Do the messages sit in the users outbox queued up?  If you run message tracking do the messages show as leaving the network?
mattconroyAuthor Commented:
Nothing in the Outbox. And nothing in the queues.
JuusoConnectaCommented:
This is only for yahoo mail or does this happen against other mail servers such as gmail or hotmail ?

You have exchange 2003 and 2010 in your exchange infrastructure, this is related to users on exchange 2003, 2010 or bouth (when sending mail to external users) ?

What's the structure of your front-end mail server ? Do you have a one ? or is exchange using its own public ip address (assuming that you have mx records configured for this as well), to send out mail ? Or does exchange 2010 send out mail by routing thru exchange 2003 ?


And a long shot, check if you've been blacklisted on: http://www.mxtoolbox.com/blacklists.aspx

cheers
mattconroyAuthor Commented:
Because SMTP outbound was using the Public MIP address the answer was to have a reverse lookup (PTR) record entered into the external DNS for the MIP.

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