Hello everyone. Hoping someone can suggest a few items for this!

We have several customers who have 1 static IP address on a DSL connection.
They run Server 2008 R2 with RDS gateway and of course zimbra.

We want to secure both email and use rds gatway on the same real world IP address.
We have enabled Application Request Routing in iis on the RDS gateway server.

We have forwarded port 443 to internal 2008 RDS server.
We then go through Application Request routing (in IIS) and under Server Proxy Settings-->we check "enable proxy" and "use url rewrite..." and check enable ssl offloading" and we point the reverse proxy to the internal ip address of the zimbra box.

We then go through the "url rewrite"section edit the created "ARR_Server_proxy" rule and add a condition "{http_host} matches pattern "mail.example.com"
https://ts.example.com goes to the RDS server and works
https://mail.example.com forwards to zimbra mail server and you can login via web interface.
PROBLEM: Active Sync does not work. what are we missing?