PST & OST Converter and Repair (EML, MBOX and PDF)

About the PST & OST Converter and Repair (EML, MBOX and PDF)

An Outlook data file keeps a whole mailbox in one file that only Outlook opens: the .pst file of a POP account or an archive, or the .ost file an Outlook.com, IMAP, Exchange or Microsoft 365 account keeps of its mailbox (Microsoft). This page turns one into files that other programs read: an .eml file for every e-mail or an .mbox file for every folder, a PDF of every folder, vCard files of contacts and iCalendar files of calendars and tasks, with repeating appointments and their changed occurrences. Attachments go inside the e-mails, and can be saved as separate files too.

Repair mode is for a file that Outlook or its Inbox Repair tool rejects: it scans the whole file for the index pages and blocks that still check out, rebuilds the folders from them, and finds deleted items whose blocks are still in the file. Everything runs in your browser, built on Microsoft's [MS-PST] specification (Microsoft Open Specifications); nothing is uploaded, and the data file is never changed. Reading, searching and the repair report are open to everyone; the exports need an Ultimate pass.

Common uses

• Moving years of Outlook mail to Apple Mail or Thunderbird.
• Keeping a readable PDF record of a project folder, a case or an account that is being closed.
• Getting mail, contacts and calendars out of the .ost of an account that no longer exists.
• Saving what is left of a .pst that Outlook and its Inbox Repair tool refuse to open.
• Turning Outlook contacts into a vCard file and calendars into iCalendar files for another address book or calendar.

Which format to choose

• EML: one file for every e-mail, in the Internet message format (RFC 5322), with the e-mail's own Internet headers when it arrived by mail, its text and HTML bodies, its attachments and the items attached to it. It suits archives, and Email to PDF reads it.
• MBOX: one file for every folder, the messages one after another (RFC 4155). Apple Mail imports MBOX files with File › Import Mailboxes (Apple), and Thunderbird with its ImportExportTools NG add-on (ImportExportTools NG).
• PDF: one file for every folder, with a list of its items that links to their pages, then each item with its header lines and text, as real text that can be searched and copied. One PDF holds up to 1,000 items and 1,500 pages; a larger folder becomes several.
• vCard 3.0 (RFC 2426) for contacts, with their names, company, e-mail addresses, telephone numbers, addresses, birthday and picture, and contact groups with their members; iCalendar (RFC 5545) for calendar items, with their time zone, repeating pattern, removed and changed occurrences and reminders, and for tasks, with their dates and status.

Repair mode: what it can and cannot bring back

An Outlook data file finds everything through two indexes, of its records and of its blocks of data (MS-PST). When a page of an index is damaged, Outlook loses the way to everything below it, although the items themselves are still in the file. Repair mode does not rely on the indexes alone: it reads the whole file, a few megabytes at a time, keeps every index page and block that passes its checksum and signature, and rebuilds the folder tree from the folders' own records, each item going back to the folder it names as its own.

Because a changed index page is written to a new place and the old one is only freed (MS-PST), older copies can still list items deleted since; when their blocks have not been reused, they come back in a folder named Deleted items found. Items whose index entry is gone come back with their own properties only (subject, sender, date and short text), in a folder of their own. What new data has overwritten is gone, and the page never writes to the file.

If you have Outlook, its Inbox Repair tool (SCANPST.EXE) repairs a .pst in place: it makes a backup with the .bak extension and puts what it cannot place in a Lost and Found folder (Microsoft). For the .ost of an Exchange account, Microsoft's advice is to delete the file, which Outlook recreates the next time it opens; an .ost whose account is gone holds the only copy, so export it here before deleting anything.

No .pst files

The converter writes EML, MBOX, PDF, vCard and iCalendar files, not .pst files, so it does not turn an .ost into a .pst. While an account still works, new Outlook for Windows can export its mailbox to a .pst (Microsoft). For an .ost whose account is gone, EML and MBOX are the formats other mail programs import.

Passwords, encryption and other people’s mail

• A .pst with a password opens only after its password is typed: the check is one every program must make (MS-PST), and the page never tries to guess a password.
• Messages encrypted with S/MIME are written as they are stored, still encrypted, because only the recipient's certificate opens them; signed messages keep their signed part as it was (MS-OXOSMIME).
• Open only mailboxes you own or may examine. The .ost of a work account is the organisation's data.

Trademarks

Microsoft, Outlook, Windows, Exchange and Edge are trademarks of the Microsoft group of companies; Apple and Safari are trademarks of Apple Inc., registered in the U.S. and other countries and regions; Thunderbird and Firefox are trademarks of the Mozilla Foundation; Chrome is a trademark of Google LLC. They are named only to say which files and programs the converter works with. MySmartCoPilot is not affiliated with Microsoft, Apple, Mozilla or Google, and none of them has sponsored or approved this page.

Limitations

• It writes EML, MBOX, PDF, vCard and iCalendar files, not .pst files.
• Messages encrypted with S/MIME stay encrypted, and files encrypted with Windows Information Protection cannot be read.
• Repair mode brings back deleted items only while their blocks are still in the file, and items found without their index entry come back with their own properties only, without recipients or attachments.
• PDFs are written in fonts for Latin, Greek, Cyrillic and Vietnamese text: characters of other scripts are written as “?” and listed in the export report. EML and MBOX files keep every character.
• In Firefox and Safari an export is downloaded as ZIP files of up to 512 MB each, one after another; Chrome and Edge can write into a folder instead.
• Attachments over 256 MB are left out of the export and named in its report.
• Repeating calendar items keep the time zone stored with them (an item stored without one keeps its times as written); other times are written in UTC, which calendars convert to local time.
• A large file takes a while: every item is read and written in turn on your device, and the page shows how far it has got.

Privacy

On this device: nothing is sent

The data file is read in your browser and the exported files are written on your device; nothing is uploaded. Use it only on mailboxes you own or may examine: the .ost of a work account belongs to the organisation.