Read thru Autodiscover whitepaper .... If I have multiple smtp domains, create a seperate website for redirect. No additional certs needed. Only caveat is users get prompted with cert message first time. If put multiple domains in cert then do I need to create seperate website for redirection still or only one site will do? Will it create multiple scp in active directory...it won't right? So, still need redirection, with all domains in cert no prompt

Autodiscover is two parts. For machines that are in the domain, and can access the domain, so are inside the firewall or on a VPN, they will all use the same URL, and that will usually be the internal name of the Exchange server. You can see that value on get-clientaccesserver under AutodiscoverServiceInternalURI. Externally, if you set your certificate with autodiscover.<domain> for every domain the server is supporting, then you just need to point the DNS record for autodiscover in each domain at the IP address for the Exchange server. No additional web sites required. Autodiscover is Host Name OR redirection OR SRV record. Not a combination. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

Thanks. How about machines that are connected to internal network, but are part of a workgroup. These can't use SCP to lookup - right? So, they use SRV records and cert will have multiple domains and SRV records ?

If you have machines on your internal network that are using your internal DNS servers, then you will need to have DNS records for their domains in place to use autodiscover. The same rules apply though, so if you are using SRV records to support multiple domains then you need to ensure that autodiscover.example.com doesn't resolve internally either, whether that is to an external or internal IP address. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.