Tiny Online Tools
Two formats, one reader
An .eml file is the message exactly as it crossed the wire: an RFC 5322 header block, a blank line, then a MIME body. An Outlook .msg is something else entirely — a compound file holding decoded MAPI properties, with the sender, recipients, subject, body and attachments stored as separate typed fields. This tool reads both and shows them through the same views, because what a reader wants from either is the same.
The file is identified by its bytes, not its extension. A .msg renamed .eml is common enough — it comes out of ticket systems and mail gateways constantly — and it opens here without complaint.
Remote images stay off
HTML mail routinely references images on the sender's server. Loading one tells the sender that the message was opened, from what address, at what time. The Show remote images switch is off, and off means the request is never made: the preview runs inside a sandboxed frame with a Content-Security-Policy that blocks every outbound connection, so nothing is merely hidden. The count of blocked references is shown, so you can see how many trackers a message carries.
Embedded images referenced with cid: are different — those parts are inside the file already, and they are inlined from the message's own bytes. Scripts, forms and frames are stripped before rendering, and the frame is granted neither script execution nor same-origin access.
What a .msg cannot give you
A .msg does not store the bytes that arrived. Outlook usually keeps the original header block in one property, and when it does, the headers view shows it verbatim. The Save as .eml button rebuilds a message from those headers plus the decoded body and attachments — a faithful reconstruction, but not the original file. DKIM signatures will not verify against it, and byte comparisons are meaningless. That is a property of the format, not a limitation of this tool.
Everything happens in this tab. No part of the message is uploaded anywhere.