Hi, I know that Exchange 2003 and 2007 can host multiple domains on the same server. I have to implement this on a customer's server, and I have found all the info on how to do it.Problem comes with rDNS. They have domain abc.com already setup with the relevent rDNS entry created at their ISP. But they now havexyz.com and want to use it as aseperate email domain on the same server to send and receive.I knowit is possible to have multiple rDNS entries on a single static IP, BUT the receiving server will only check the first record. How do I get receiving servers to accept mail from the secondary domain without an rDNS entry? Would I need to use a SmartHost? And would this provide outgoing mail with the relevent rDNS response?Thanks in advance.

Hi, Please understand that receiving servers check the Reverse DNS record and reject the email themselves. From sender end, we have no method to control how receiver end check Reverse DNS record and how they handle the emails. Therefore, for your end, I suggest you have the outbound email for the secondary domain have another IP Address. Then, you can create a new Reverse DNS record for the secondary domain by using another IP Address. Mike

Hi Mike,Thanks for your reply.Out of interest, how do Exchange hosting companies handle the issue of rDNS? Some companies must have hundreds of clients - do they use a generic rDNS entry?Dom

Hi Dom, Firstly, please understand that the Exchange does not rejected messages even the Reverse DNS lookup failed. For your reference: The "Perform Reverse DNS Lookup for Incoming Messages" Option Is for Host Name Resolution http://support.microsoft.com/kb/297412/en-us In addition, according the above article: If you select the Perform Reverse DNS Lookup for Incoming Messages option, the SMTP service tries to verify that the clients IP address matches the host and domain that is submitted by the client in the EHLO/HELO command. The Exchange server performs Reverse DNS Lookup by using the host and domain that is submitted by the client in the EHLO/HELO command. Therefore, I think that the Reverse DNS lookup will success if the host and domain name matches the IP Address. You can configure the host and domain that is submitted by the client in the EHLO/HELO command on the SMTP Virtual Server->Delivery tab->Advanced->Fully-qualified domain name. Therefore, I think that the issue does not relate which domain the message is sent from. Mike