Bring in old mailboxes: PST, OLM, Apple Mail and more

What can be brought in

Drop a file or folder on MailVault or choose it under Import. The format is recognised; you do not have to name it.

Messages are brought in with their attachments. Nothing is passed over in silence: at the end the import names every message it could not bring in, with the reason, and its entry in the audit journal counts them as failed.

PST on a Mac, without Outlook

A PST file is the format in which Outlook for Windows keeps mailboxes and archives. On a Mac it cannot simply be opened. MailVault reads it itself and needs neither Outlook nor Windows nor a virtual machine. The same goes for single Outlook messages saved as .msg.

An OST is the offline copy of an Exchange or Microsoft 365 mailbox. If the mailbox is still reachable, collect it from the server over IMAP instead: there the messages are as they were delivered, and that is worth more than any reconstruction.

What becomes of an Outlook file

None of the four Outlook formats keeps the message a mail server delivered. OLM keeps XML fields; PST, OST and MSG keep MAPI properties, the parts of a message after Outlook has taken it apart. From these MailVault builds a faithful rendering: subject, addresses, dates, body and attachments.

That rendering is marked as such, in four places:

• in the archive's database,
• in the audit journal,
• in the compliance report, under “Message provenance”,
• in the message itself, in an X-MailVault-Origin header, so an exported copy still says what it is.

Where Outlook kept the headers the message actually arrived with, they are used as they stand. The chain of Received lines, the original Message-ID and any DKIM signature survive; only the headers describing the re-encoded body are replaced.

If an attachment could not be read, or Outlook kept only a link to a file on a network share instead of the file, the rebuilt message says that too, in a header of its own, X-MailVault-Missing-Attachment. Every export carries the note with it.

Imported twice is stored once

The same import produces the same bytes every time. Reading a PST in twice by mistake, or starting again after an interruption, creates no duplicates: the archive recognises the messages by their SHA-256 and does not store them again.

From Apple Mail and Thunderbird

Apple Mail keeps its mailboxes as folders of individual .emlx files, and MailVault reads that folder directly. Single mailboxes you saved from Mail with Mailbox ▸ Export Mailbox are .mbox packages and are recognised too. A Thunderbird profile is brought in as a whole.

macOS opens Apple Mail's mailbox folder to MailVault only with Full Disk Access, or when you choose the folder yourself in the Open panel. Without that access, MailVault says so before it reads anything, and offers both: the way to the privacy settings and choosing the folder.

These formats hold the message as it was delivered, so they do not count as renderings.