Why won't my .msg file open?

Symptom: nothing happens, or "no application can open this file"

Cause: no handler is registered for the format. This is the normal state on macOS, Linux, iOS and Android, and on Windows machines without Outlook installed.

Fix: open it in the browser viewer, which needs nothing installed. Platform-specific steps are in the Mac guide and the phone guide.

Symptom: it opens in Notepad or TextEdit as binary garbage

Cause: your system fell back to a text editor. The file is fine; a text editor simply cannot interpret a binary container.

Fix: on Windows, right-click the file, choose Open with, and pick Outlook — or use the browser viewer. Do not be alarmed by the garbage: seeing fragments of the message text scattered through it actually confirms the file is intact.

Symptom: the message opens but the body is blank

This is the most common failure in other online viewers, and it is worth understanding because it is not your file's fault.

Cause: Outlook can store the body in three different places — plain text, HTML, or compressed RTF with the original HTML encapsulated inside it. That third case is extremely common: in a sample of 20 real business messages, 17 stored their body only as compressed RTF. A viewer that reads the HTML property and gives up when it is missing shows nothing at all.

Fix: use a viewer that decompresses the RTF and de-encapsulates the HTML from it. This site does that, so try the same file in the viewer before concluding it is empty.

Symptom: images in the message are missing or show as empty boxes

Cause A — remote images are blocked. Images hosted on the sender's server are blocked by default here, because they are routinely used as tracking pixels that report when you opened the message. Use Load images in the banner to fetch them.

Cause B — unresolved inline images. Images embedded in the message are stored as hidden attachments and referenced as cid:something@01D9…. A viewer has to match each reference back to its attachment. If it does not, you get broken-image placeholders where the signature and logos should be.

Symptom: non-Latin text is mojibake

Cause: the HTML body is stored as raw bytes that must be decoded using the code page named in the message's own properties. Decoding it as UTF-8 by default turns Chinese, Japanese, Korean, Cyrillic and Greek messages into nonsense.

Fix: use a viewer that reads the declared code page. If a message looked like garbage elsewhere, it is worth retrying here.

Symptom: "the file is corrupted" or it will not parse

Work through these in order:

1. Check the size. A file of 0 bytes, or a few hundred, did not transfer completely. Ask the sender to send it again — ideally zipped, since some mail gateways strip or truncate .msg attachments.
2. Check it is really a .msg. Every genuine one starts with the same eight signature bytes. This viewer detects the real format from those bytes rather than the extension, so a mislabelled .eml renamed to .msg still opens.
3. Check whether it was edited. Opening a .msg in a text editor and saving it will destroy the binary structure irreversibly. Always work on a copy.

Symptom: it asks for a password, or the body is unreadable ciphertext

Cause: the message is encrypted with S/MIME.

Fix: there is no workaround. Decryption requires the private certificate the message was encrypted to, which lives in the intended recipient's certificate store and is not available to a browser. Digitally signed messages are different — those read normally, with the signature shown as an attachment.

Symptom: the attachment list looks wrong

Inline images are technically attachments too — a long reply chain can carry a dozen signature logos. Listing them alongside the real attachments makes it hard to find the document you actually want, so they are shown in the body instead and kept out of the list. If an attachment you expected is missing entirely, check whether the sender's mail gateway stripped it before it reached you; the FAQ covers what the raw headers can tell you about that.