Free .msg viewers compared: which upload your email?
Four free .msg viewers checked on 30 September 2026: which send your email to a server, their size limits and formats, and how to check any viewer yourself.
Short answer: two of the four upload the file to their own server before showing it; two read it inside your browser and send nothing. If the email is confidential, use one of the two that stay local, or check for yourself in under a minute.
The comparison
Checked on 30 September 2026 by reading each site's own page and upload code. No file was uploaded to any service to produce this table.
| Tool | Where your file goes | Size limit | Notes |
|---|---|---|---|
| MsgLens (this site) | Stays in your browser | 100 MB | .msg, .eml and winmail.dat; attachments; PDF and .eml export. Open source (MIT). |
| msg-viewer.pages.dev | Stays in your browser; its code contains no upload call | Not stated | .msg; its code includes attachment handling. Open source. |
| Encryptomatic Viewer | Uploaded to its server (form upload) | 75 MB | .msg, .eml and winmail.dat; attachments. |
| CoolUtils MSG to PDF | Uploaded to its server; it says uploads are deleted within 24 hours | 50 MB | A converter rather than a viewer: outputs PDF, DOC, HTML, JPG or TXT. |
Both local tools load a third-party script: msg-viewer.pages.dev loads Google Analytics, and this site loads Google AdSense. Neither sends the file. Whether the other tools render messages whose body is stored only as compressed RTF was not tested; that would have meant uploading a message to them.
Why it matters for email in particular
A saved .msg is rarely a newsletter. It is a forwarded offer letter, a contract thread, a complaint with the customer's details in the signature. Uploading it to read it hands a complete copy, headers and attachments included, to a server you know nothing about. A deletion promise may well be kept, but it is a promise; a viewer that never sends the file does not need one.
How to check any viewer yourself
- Open the viewer, then open your browser's developer tools (F12, or Cmd+Option+I on a Mac) and choose the Network tab.
- Open a .msg file in the viewer.
- Look for a request the size of your file, usually a
POST. If there is one, the file was uploaded. If the only requests are small ones for scripts or ads, it was read locally. - Stronger test: load the viewer, disconnect from the network, then open a file. A local viewer still works; an uploading one cannot.
When uploading is fine
For a message you would happily post publicly, any of these tools will do, and a converter such as CoolUtils offers output formats a viewer does not. The choice only matters when the content is private, which for saved email is most of the time.