About
What this is
MsgLens opens Outlook .msg files, standard .eml files and winmail.dat (TNEF) attachments in a browser, without Outlook and without installing anything. It reads the message the way Outlook would: formatted body, inline images, attachments, and the raw internet headers.
Why it exists
.msg is a Microsoft-only container format, so a file that arrives from a colleague on Windows is unopenable on a Mac, a phone, or in Gmail. The tools that already answered this either upload your file to a server you know nothing about, or show the message body and nothing else.
Business email is a bad thing to post to an unknown server. So this was built the other way round: the parsing runs in your browser, and there is no upload endpoint for it to be posted to.
How it works, and how to check
The viewer has no server side. Your file is read by JavaScript in your own tab, and you can verify that in two ways that do not require trusting this page:
- Open your browser's developer tools, switch to the Network tab, and open a file. No request carries it.
- Disconnect from the internet after the page has loaded, then open a file. It still works.
There is one exception and it is opt-in: if you sign in and choose Save to workspace, that file is uploaded so your colleagues can open it. Opening a message never saves it. The privacy policy sets out exactly what is stored in that case.
What it does not do
Worth being explicit about, because the gaps are not obvious from the outside:
- It cannot decrypt S/MIME-encrypted messages. That needs the recipient's private certificate, which a browser has no access to. Signed messages read normally.
- It does not connect to a mailbox. It reads files you already have; it is not a mail client and has no access to any account.
- It cannot recover a recipient list from a
winmail.dat, because that information was never in the file — see the winmail.dat guide.
Who runs it
MsgLens is built and maintained by Andy Liu, working independently. It is not a company, and it is not affiliated with, endorsed by or sponsored by Microsoft in any way. Microsoft, Outlook and Exchange are trademarks of Microsoft Corporation.
One person reads the mail, writes the guides and fixes the bugs. That is worth knowing both ways: a reply takes a few days rather than an hour, and there is nobody to hide behind if something here is wrong.
Running costs are covered by advertising, which is why you will see ads on the guides and around the viewer. Ads never appear inside a message you have opened, and no message content is ever passed to an advertiser — there is no mechanism by which it could be, since the content never leaves your browser.
Questions, bug reports and corrections are welcome: get in touch.