MSG File Viewer

Why .msg files are hard to open without Outlook

A .msg file isn't a plain-text email like a .eml file — it's Microsoft's proprietary CFBF (Compound File Binary Format, the same OLE2 container format used by old .doc and .xls files) packed with binary MAPI property streams. That format is undocumented outside Microsoft's own reference implementation, which is why Mac Mail, Gmail, Thunderbird, and most email clients that aren't Outlook simply can't open a .msg attachment at all — double-clicking one on a Mac just downloads a file nothing recognizes. This tool uses msgreader, an open-source, community-reverse-engineered CFBF/MAPI parser, running entirely in your browser, to read that binary structure and pull out the readable email underneath.

Real situations this is built for

• Legal discovery / eDiscovery review — opposing counsel or a client hands over a folder of exported .msg files and you need to read them without installing Outlook or a forensic email suite.
• IT and mailbox migration audits — checking the contents of an old .msg archive pulled from a decommissioned mailbox or backup.
• Mac users with no Outlook install — someone emails you a .msg attachment (common when a Windows/Outlook user forwards an email as an attachment) and you just need to read it once.
• Quick forensic or investigative review — checking headers, sender, and attachment names in a single suspicious message without opening it in a full mail client.

Private by design

There is no upload endpoint on this site. Your .msg file is read using the browser's built-in File API and handed directly to the parser running in your own tab — open your browser's DevTools, watch the Network panel, and open a file: no request carrying your file's contents will appear. The page works offline after the first visit, which wouldn't be possible if reading a message required a server round-trip.

FAQ

Is my email file uploaded anywhere?

No. Parsing happens entirely client-side in your browser using JavaScript — no server ever receives your file. See the privacy policy for full detail.

What if my file won't parse?

It's most likely corrupted, not actually a .msg/CFBF file (renamed extension), or an unusual older Outlook variant the open-source parser doesn't cover. This tool uses a community, reverse-engineered parser rather than Microsoft's own code, so it aims for broad compatibility but can't guarantee every possible .msg variant ever produced.

Can I open an attachment that is itself another email (a nested .msg)?

Outlook does let you attach one email to another. Today this tool lists a nested .msg attachment as a regular file you can download — to read that inner email, download it and drop the downloaded file back into this same tool.

Does this replace Outlook?

No — it's a fast, private, read-only viewer for one-off situations where installing or licensing Outlook isn't practical. It doesn't send mail, edit messages, or connect to any mail server.

Can I download the original attachments, not just the text?

Yes — each attachment listed gets its own "Download" link that extracts the original file bytes and saves them locally, using your browser's normal download mechanism.