Its widespread use makes email one of the most common threat vectors targeted by cyber criminals. However, if they are managed incorrectly, they can become corrupted or create a major security issue. PST files are an extremely common form of email storage, which are central to all Microsoft email software solutions. This helps users access emails even when they are not connected to the email server. ost files are used as a temporary offline storage option for Exchange servers and webmail hosts, such as. pst extension in an Outlook data folder, while. This data can either be compressed or encrypted, and Outlook’s performance slows down as the PST file accumulates more data.

This also enabled users to expand their email storage space by creating local archives.Įvery email account created in Outlook gets its own database, which is the PST file that stores contacts, calendar items, emails, and reminder messages. But PST files were originally used to help admins limit the amount of storage available on their servers to improve performance and reduce backup times. Some Microsoft accounts, such as Post Office Protocol (POP) accounts, store information in Outlook Data Files (.pst), while others, such as Outlook 365, Exchange, Internet Message Access Protocol (IMAP), and accounts, store information in Offline Outlook Data Files (.ost).Īrchiving emails is now associated with terms and practices like electronic discovery (e-discovery), compliance, and regulation. This enables users to access emails they have previously downloaded or synchronized, contacts and calendar information, and tasks even if they are not online. When a new email account is added to Outlook, Outlook creates a local copy of the information onto the user’s device. It was used to help users access server mailboxes, and just like in the modern day, allow them to create local archives of the email folders they have on server-based email clients. The format first appeared in the mid-1990s in the Microsoft Exchange email client, which later became Microsoft Outlook. The PST file format is also commonly referred to as a personal folder, or when used as a cache in Outlook’s exchange mode, an offline storage table (OST) or offline folder. PST files are stored within popular Microsoft software like Microsoft Exchange Client, Windows Messaging, and Microsoft Outlook. A PST file is a personal storage table, which is a file format Microsoft programs use to store items like calendar events, contacts, and email messages.

Outlook pst files windows 10