I edited this to try make it a little clearer....

In a shared server environment (Mosso Cloud Servers). I have setup a DNN4 installation and it works fine with the default portal.
However I have about 20 other portals / domains, in the same installation.

In my old IIS setup, I used to just add these URLs to the multiple identities / host header section in the IIS manager. Then DNN would show the correct portal based on the domain header info.

However with this shared environment, I cannot do that. I can create a domain alias to point to the domain of the main installation but then Mosso does not allow separate email accounts for an alias. eg bob@domain1.com and bob@domain2.com.

So I have to create each portal as a full new website, with email. No Problem.

I want any traffic coming to domain2.com to get forwarded to domain1.com but still maintain the header name (domain2.com), so that it launches the correct portal.

A 301 redirect does not seam to work because it just launches the domain1.com portal. It doesn't know that it came from domain2.com.

Short of a separate DNN installation for each domain/portal, I cannot figure out how to do this.

Any Help ?