The Free/Busy feature allows users to view each other’s calendars for efficiently scheduling meetings. You can set up free/busy scheduling across ECS and Microsoft Exchange servers.
The EhloMail foreign principal is usually the user's address. This is a multi-value attribute, you can add more than one account address. A prefix is added to the address. This sets up a mapping from the ECS account to the corresponding object in the Active Directory.
In the Free/Busy Interop Provider drop-down menu, select the interop provider.
In the Foreign Principal Email address text box enter the account's user's address.
Click OK. The dialog box closes and the name is added to the Foreign Principals content pane.
Select the address and click Push. This schedules the free/busy information to be pushed to the provider and makes the accounts free busy status available.