How to open an MSG file
Outlook saves messages in a format only Outlook understands. Here is how to read one when you do not have it.
Open your MSG file now
Drop the .msg file in and read the sender, the message and the attachment list. Outlook not required, nothing uploaded.
Open the MSG viewerOr read why the format is awkward first.
Why nothing opens it
Unlike .eml, which is plain text that any program can read, a
.msg file is a binary container — the same OLE2 compound
format used by old .doc files. Inside it, the message is stored as a set of
Microsoft MAPI properties rather than as standard headers.
That is why double-clicking does nothing on a Mac, on Linux, on a phone, or on any Windows machine without Outlook installed: the format is Microsoft's, and so is the only program that reads it by default.
Reading one in the browser
- Save the
.msgfile somewhere you can reach it. - Drop it into the viewer above.
- The subject, sender, recipients, message text and attachment list appear.
The format is detected from the file's signature rather than its extension, so a message that was renamed by hand — which happens often when files travel through several systems — is still read correctly.
One honest limitation
Formatting
Outlook stores the formatted version of a message inside compressed RTF rather than as HTML. We do not decompress it, so what you see is the plain-text body: the words, without the fonts and colours. Everything that matters for reading or filing the message — sender, recipients, date, text, attachments — is there.
Turning it into something portable
If the message needs to go into a case file or a document system, export it as a PDF:
it opens anywhere and does not depend on Microsoft software still being installed in
five years' time. The conversion to PDF works the same
way for .msg as for .eml.