ExchangeOnlineArchiving assists with archiving, compliance, regulatory, and eDiscovery while simplifying onpremises infrastructure, reducing costs, and easing IT burdens. Online or personal archives is a service in Office365 that provides an additional user mailbox for storing older messages, such as calendar items from two or more years ago or sent items that are no longer of immediate importance. The online archive mailbox looks just like an ordinary mailbox and you can create folders in it, search it, and carry out the same administrative tasks as with a regular mailbox. The chief difference between the online archive and the main mailbox is that the online archive can be much larger – useful for CEOs who do not like deleting anything – and the fact that it is not available offline, so does not create a corresponding offline store (.OST) file on the local computer.