Hi, we have mailboxes on 2010 that when they send email the firewall is throwing that traffic over to the pool that all internet traffic is going out of. As a result recipient domains are blocking those messages. The host names of the severs are being listed in the headers along with that interent traffic pooled IP address, neither of which is known for email externally. On the other hand, mailboxes on 2007 go to the firewall and it directs them to the exchange 2007 external namespace. What do we need to do to fix this for the exchange 2010 messages? Do we need to create an external namespace for every one of our CAS/HUB servers and an external IP for them? Or should we have 1 generic external namespace tied to an IP that we NAT in the firewall? Or is there another way with RDNS? Thanks.

Nevermind....we pointed mail to our barracuda for outbound filtering and there was already a NAT and RDNS setup for that external IP.