ActiveSync not work in hosted exchange environment

I have a server set up as w2003AD with a single forest and domain named
x.y.com. On this server, we installed exchange2003 with SP1. We host
mailboxes for different customer from different company. And each company has
their own email domain, eg or .
they also have their own specific UPN in AD that follow their email domain.
I can use OWA and outlook and RPCoverHTTP to connect to these user mailboxes.
But when I tried to use PocketPC to sync remotely to the exchange server for
these user, I always get error Http_500.
If I could to change the email address of these users to the default
then I can sync using the pocketPC remotely.

Would like to know, does activeSync support the type of environame I had,
where each comapny hosted in the same exchnage server and AD has different
email domain?
Why OWA, outlook client can connect whereas activesync cannot?
Can ActiveSync support authentication using UPN on the PocketPC?

All Advise and direction given is greatly appreciated.

Regards
Vic

Sorry Vic but EAS does not support hosting.
Thx

"Vic" wrote:

> I have a server set up as w2003AD with a single forest and domain named
> x.y.com. On this server, we installed exchange2003 with SP1. We host
> mailboxes for different customer from different company. And each company has
> their own email domain, eg or .
> they also have their own specific UPN in AD that follow their email domain.
> I can use OWA and outlook and RPCoverHTTP to connect to these user mailboxes.
> But when I tried to use PocketPC to sync remotely to the exchange server for
> these user, I always get error Http_500.
> If I could to change the email address of these users to the default
> then I can sync using the pocketPC remotely.
>
> Would like to know, does activeSync support the type of environame I had,
> where each comapny hosted in the same exchnage server and AD has different
> email domain?
> Why OWA, outlook client can connect whereas activesync cannot?
> Can ActiveSync support authentication using UPN on the PocketPC?
>
> All Advise and direction given is greatly appreciated.
>
> Regards
> Vic