To archive user mailboxes, there must be one Exchange Mailbox Archiving Task for each Microsoft Exchange Server computer that is being served in the Enterprise Vault site. A Microsoft Exchange Server can be served by only one Exchange Mailbox Archiving Task. However, there can be more than one Exchange Mailbox Archiving Task running on the same computer in an Enterprise Vault site, servicing different Microsoft Exchange Servers.

The Exchange Mailbox Archiving Task interfaces most directly with Microsoft Exchange Server (using MAPI), the Storage Service and the Indexing Service. Therefore, it makes most sense to install the task on the same computer as the Storage Service and Indexing Service with which it interfaces. This reduces the amount of data that has to cross network links.