About the Exchange Service Account
The user account under which the Exchange Connector runs is known as the Exchange service account. The Exchange service account must have read-write privileges to the Microsoft Exchange mailboxes of all synchronization-enabled users. Therefore, the Exchange service account must be a domain account, not a local account.
Provided there are trust relationships between all the Active Directory domains in which your Exchange Servers are deployed, you require only one Exchange service account for your whole Microsoft Exchange infrastructure, regardless of how many Exchange Servers you have. Exchange Servers are not listed in the Siebel database. Instead, the Exchange Connector queries the Active Directory Global Catalog at runtime to determine which Exchange Server handles the mailbox for a given user (SMTP email address).
To manage the process of giving the Exchange service account read and write access toSSSE user mailboxes, you can use a script that gathers information about the applicable users from the Siebel User Map view. For more information about the script, see Configuring User Mailbox Access for the Exchange Service Account.