Systems and methods for performing backup operations and other secondary copy operations for mail servers, such as Exchange servers, are described. In some cases, the systems and methods perform multi-streaming backup and other copy operations using a single mailbox agent, which launches backup streams via a coordinator that determines when to launch streams, at what mailboxes (or folders) to launch the streams, and so on. The coordinator communicates with controllers at different machines (e.g., servers) to be backed up, and may assign streams, mailboxes, and so on, to the different controllers, which perform the backup operations for their assigned mailboxes and/or clients.