Hi,

Finally a nice write-up on the different options you have with Provisioning Mail Enabled objects on Exchange 2003-2010. The article describes both Identity Lifecycly Manager 2007 Feature Pack 1 (ILM2007FP1) and Forefront Identity Manager 2010 (FIM2010).

With Exchange 2003 it's the RUS that completes the provisioning process once the objects have been created in AD.

For Exchange 2007 & 2010, once the objects are created in AD, you'll need to run the Update-Recipient cmdlet to complete the provisioning process.

The difference with FIM 2010 is that instead of running the update-recipient cmdlet locally on the provisioning server it can be remotely executed using Remote Powershell.

Happy reading  --> http://technet.microsoft.com/en-us/magazine/ff472471.aspx