Slow Outlook connectivity to Office365 behind proxy

Hi,

We're migrating to Office 365 fully in the cloud.

We've noticed that all Outlook clients take few minutes to connect to Exchange server.

Found the workaround to add registry key:

HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\RPC\EnableForceHttpProxy value 1

However this is only works while in the office. If user tries to connect from home it forces proxy connection which results in no connectivity at all.

Un-checking Bypass Proxy for Local Addresses works but this setting needs to be on in our environment...

Any ideas?

Thanks