Open a PST file without Outlook

The Outlook file

What a .pst file is

A .pst is where Outlook keeps email on your computer: an archive you exported, the file Outlook calls Personal Folders, or an old mailbox from a job. An .ost is the copy Outlook keeps of a Microsoft 365, Exchange or Outlook.com mailbox. Both are Outlook's own database format, and nothing but Outlook opens them. Without Outlook, on a Mac, a Chromebook or a phone, the usual advice is to buy a converter.

How it is read

• In this tab, from the file itself. CABINET reads Outlook's format as Microsoft documents it: the indexes, then only the parts of the file each folder and message needs, when it needs them, so a large file is never uploaded or held in memory.
• Every folder, with its emails, contacts and calendar entries. Emails open with their sender, recipients, text, pictures and attachments. An email attached to an email opens and saves too.
• Into formats everything reads. Any email saves as an .eml, which Apple Mail, Thunderbird, Outlook and Gmail's importers open. A folder, or every email in the file, saves as one .mbox, which Thunderbird and Apple Mail import and POSTBAG opens.
• Nothing in an email runs or reports back. HTML email is shown in a sealed frame: scripts and forms are taken out, links do nothing, and pictures that live on the internet are not loaded, since loading one tells the sender the email was opened.

What it does not read

Two kinds of .pst are recognised and named rather than guessed at: files in the Outlook 97 to 2002 format, from before Outlook used Unicode, and files made with Outlook's "high encryption" setting. Outlook 2003 or later can open either and save a copy in the current format. A password set on a .pst is not encryption and is not needed here. Contacts and calendar entries open as items but are not written into the .mbox, which holds email only.