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Open Outlook .msg Files

Read a .msg without Outlook installed. Message, headers and attachments — all in your browser, nothing uploaded.

Your files stay safe — processed entirely in your browser. Nothing is uploaded.

Drop a .msg file here

or click to select a file

Outlook message files (.msg). Nothing is uploaded.

How this MSG viewer works

A .msg is not an email file in the usual sense. It is a compound file — a small FAT filesystem inside a single file — and the message is spread across streams named after the MAPI property each one holds.

That container is the same one .doc, .xls and .ppt use, which is why all four share a single signature and have to be told apart by what is stored inside them.

Reading the container
The reader walks the CFB structures directly: the header, the FAT and its DIFAT continuation, the directory tree, and the mini FAT. No library sits in between, so nothing has to be uploaded for a server to do it.
The mini stream matters
Streams under 4096 bytes are packed into 64-byte mini sectors carved out of one ordinary stream. Almost every MAPI property in a message is that small, so a reader that skips the mini FAT reads essentially nothing. Both paths are covered and both are tested.
Property streams
Each property is a stream called __substg1.0_ followed by the property id and type in hex — 0037001F is the subject as Unicode, 0037001E the same subject in the message code page. Fixed-length values such as timestamps are packed into __properties_version1.0 instead.
Filename resolution
Attachment names come from PidTagAttachLongFilename (0x3707), then PidTagAttachFilename (0x3704), then PidTagDisplayName (0x3001). Reading only the short name is what produces 8.3 mojibake for Japanese filenames — the same trap as in winmail.dat, and handled the same way here.
HTML safety
PR_HTML is binary and follows the message code page rather than being Unicode like the other text. Once decoded it is sanitized with DOMPurify against an explicit allowlist and rendered inside a sandboxed iframe.

Where it stops

Messages embedded inside other messages are listed but not opened as messages. RTF-compressed bodies (PR_RTF_COMPRESSED) are not decompressed — if a message has only an RTF body and no plain-text or HTML version, the body will be empty. Encrypted or signed S/MIME content is not decrypted.

Frequently Asked Questions

What is a .msg file?
A .msg file is a single Outlook message saved to disk — the body, headers and every attachment packed into one file. It is not a standard email format: internally it is a compound file, the same container Microsoft used for .doc and .xls, which is why other mail clients cannot open it.
Do I need Outlook installed?
No. This viewer reads the file structure directly in your browser, so it works on any machine, including one that has never had Outlook on it.
Is my message uploaded anywhere?
No. The file is read in your browser and no part of it is sent to a server. You can confirm that by opening your browser's Network tab while you use the tool.
Can I get the attachments out?
Yes. Every file attachment is listed with its real name and size, and can be downloaded individually or all at once as a ZIP built in your browser.
Why do other tools show Japanese attachment names as gibberish?
An attachment can carry its name in several MAPI properties. The short, legacy one is code-page dependent and often truncated. This viewer prefers the Unicode long filename, so names in Japanese and other non-Latin scripts survive intact.
What is the difference between .msg and .eml?
.eml is a standard MIME message — plain text you could read in an editor. .msg is Outlook's own binary container. If you need a portable copy, save as .eml; if someone sent you a .msg, use this viewer.
Are there messages this cannot open?
Messages whose body exists only as compressed RTF will show an empty body, embedded messages inside a message are not expanded, and encrypted or signed S/MIME content is not decrypted.