These instructions apply to Outlook for Microsoft 365. Select the links to the Microsoft documentation to learn more about each topic.

• In a Microsoft Exchange Server account, you can decide how much mail is available when working offline with a slow or no network connection.
  • Read more: Work offline in Outlook.
• Email messages, calendar, tasks, and other items are saved on a mail server, on your computer, or both. Outlook items that are saved on your computer, are kept in an Outlook Data File (.pst and .pst).
  • Read more: Manage and organize.
• When your online mailbox is near your storage quota, you could move some items to an Outlook Data File (.pst). Older messages and items that you don't use regularly can be archived in an Outlook Data File (.pst).
  • Read more: Create an Outlook Data File (.pst) to save your information.
• An Outlook Data File (.pst) contains your backed-up email messages, calendars, contacts, tasks, and notes, and can be stored in one of the default locations.
  • Read more: Find and transfer Outlook data files from one computer to another.
• You can move old items you want to keep to an archive, which is a separate Outlook Data File (.pst) that you can open from Microsoft Outlook anytime you need it.
  • Read more:
    
    • Archive older items manually
    • Archive older items automatically