I have an ISA 2006 on running on a Windows 2003 box with multiple public address assigned to the external NIC, ranging from 120.x.x.2 to 120.x.x.5. The internal network uses NAT and running Exchange 2007 on one of servers(windows 2008). I set up the MX record point to 120.x.x.3 and create SMTP server publishing rule on ISA. The problme arise when some email servers block me due to lack of a reverse DNS record. Icheck out the error message and find out they believe the emails are sent from 120.x.x.2, not 120.x.x.3. I realized even if I have multiple public IP addresses on the ISA, I can't choose which IP address Exchange to use to send out emails to internet. Anyone has a solution? General speaking, why hosts on the internet can only see 120.x.x.2? How can I make other IP visible when SENDING OUT something?
Sorry to drum up and hijack this old thread, but it relates to what I am getting ready to do. Let's assume TMG is not a budget option.
So, the failures the OP saw were due to mismatch in sending IP of the ISA server versus the IP for the MX record. I am currently upgrading to a new Exchange server from Exchange 03 to 07. The old Exchange 03 server sends and receives through an oooold ISA 2000 box with addresses from a /29 subnet. I am about to change my MX record to a /25 subnet so when I finish moving the traffic over to our ISA 2006 box we have many more IPs available to use for web publishing and such, but want to make sure I don't assign it an address that will run into same issue.
Anyway, I just want to make sure I understand, for smtp to work without the mismatch issue, you have to make sure the first IP bound to the external NIC is the same as the MX record in the public DNS? As long as that is the case, all is good?
And while I'm at it, OWA's listener and a Barracuda Spam appliance server publishing rule and such can (must) all use that same IP without any issue, correct?
< Message edited by manning -- 26.Jul.2011 3:39:23 PM >