I've recently set up a second Exchange 2003 (sp2) server in our domain on a new member server. The intention is to eventually remove Exchange entirely from the first Win2k3 SBS. The installation went smooth and the transfer of mailboxes off of the first server and onto the second was very smooth and seemless to the end users. We haven't taken the first Exchange offline yet, though, because we can't tap into the router to change the port forwarding to the new server's IP.
The problem I'm now having, though, is that many emails to the outside world are generating underliverable notices and seem to be getting flagged as spam. I have looked up our IP on mxtoolbox.com to make sure we're not blacklisted. Why all of a sudden would our emails seem to be spamish now with a second server? Is there maybe something I missed in the configuration? I'd like to think that this problem will go away once we take the old Exchange server offline and get mail delivery to/from the new one directly with the correct router port forwarding. But until then....is there something I need to tweak on the servers themselves? DNS issue? Reverse lookup issue? Relay?