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CantOpen

Open an OLM file online

Read the mail, contacts and calendar in an Outlook for Mac archive (.olm) on Windows, a Chromebook or any computer. The archive is read in your browser and never uploaded.

Drop your .olm file here

or

Your file stays on this device: it is read here, in your browser, and never uploaded.

An Outlook for Mac archive (.olm). It stays on your device: only the parts needed are read.

How it works

  1. Choose the .olm file

    From your disk or a USB drive. It stays where it is: the browser reads only the parts it needs.

  2. Browse the archive

    Mail folders of “On My Computer” and of each account, with contacts, calendar, tasks and notes. Search a folder by subject, sender or the names in the To line.

  3. Read and save

    Open a message with its formatting and attachments, save attachments, or save the message as an .eml file. To move everything into Outlook for Windows, <a href="/convert-to-pst">convert the archive to PST</a>.

OLM files, explained

What an .olm file is

An .olm file is an archive made by Outlook for Mac: Tools → Export (File → Export in older versions) saves the mail, contacts, calendar, tasks and notes you choose into one file. Outlook for Mac 2011, 2016, 2019 and Microsoft 365 write it, and it is the export format Microsoft documents for legacy Outlook for Mac.

Inside, an .olm is a ZIP archive of XML files: one file per message, one file for the address book, one for the calendar, plus the attachments. That is why a ZIP tool can open it, but shows thousands of XML files instead of email.

Why it won’t open

  • You are on Windows. Outlook for Windows cannot open or import an .olm file: its data files are .pst and .ost.
  • The Mac or the account is gone. Outlook for Mac imports an .olm back (File → Import), but only on a Mac with Outlook installed.
  • Another mail program. Apple Mail, Thunderbird and Gmail do not read .olm files.

What this viewer does

  • Opens large .olm archives without loading them whole: it reads the archive’s directory, then one page of a folder and one message at a time.
  • Shows the mail folders of “On My Computer” and of each account, and lists contacts, calendar events, tasks and notes as items with their details.
  • Shows a message with its sender, recipients, date, text and attachments; HTML emails are shown in a locked-down frame, without scripts or remote images.
  • Searches the newest 20,000 items of a folder by subject, sender and recipients.
  • Saves attachments, and saves any message as an .eml file that Outlook, Apple Mail and Thunderbird open (free).
  • Converts the whole archive, or one folder, to an Outlook .pst file on the conversion page (paid).

What it does not do

  • It does not change the archive.
  • Contacts and calendar events are shown as lists of their details, not as an address book or a calendar.
  • Categories, flags, contact photos and contact groups are not shown.

Why the file is not uploaded

An archive holds years of private and business mail. Here the browser reads the file from your disk on demand: the folder list, a page of messages, one message. No code on the page sends the file or its name anywhere, not even to our own domain.

Frequently asked questions

How do I open an OLM file on Windows?

Choose it here: its folders, messages, contacts and calendar appear in your browser. Outlook for Windows cannot open .olm files; to get the items into it, convert the archive to a .pst file first.

Is my OLM file uploaded?

No. It is read by code running in your browser and never leaves your computer.

Can I convert OLM to PST?

Yes, on the conversion page: mail, contacts, calendar events, tasks and notes go into one .pst file for Outlook for Windows, which you open with File → Open & Export → Open Outlook Data File. The conversion is a paid feature; during the launch it is free too. Reading the archive and saving single messages stay free.

Which Outlook for Mac versions are supported?

The viewer was tested on real archives from Outlook for Mac 16, the version behind Outlook 2016, 2019 and Microsoft 365 for Mac. Archives from Outlook for Mac 2011 should open too, but we have not had one to test. If yours does not open, write to support@cantopen.com.

How large an archive can I open?

Large archives open, because the archive is read piece by piece: opening reads its directory and the address book, calendar, tasks and notes (up to 64 MB each); each message is read when you open it. The limits are 2,000,000 files inside the archive and 20,000 folders.

Can I save all the messages at once?

Here you save messages one at a time, as .eml files, for free. To keep everything together, convert the archive to a .pst file on the conversion page (paid).

The archive opens in a ZIP program. Is that normal?

Yes. An .olm is a ZIP of XML files; this viewer reads those files and shows them as email, contacts and calendar.

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