Open a .eml file in your browser
Drop a saved email and read it here — inline images resolved, in desktop or phone width, with a simulated dark-mode view. No client, no install, no upload: the file is parsed inside this tab.
Free · no signup · parsed locally in your browser
What is actually inside a .eml file
One text file, a handful of parts, and a rule about images that explains most of what confuses people.
A .eml file is one message in MIME format: a block of headers, then the body split into parts — usually a text/plain alternative and a text/html version inside a multipart/alternative container, wrapped again in multipart/mixed if there are attachments.
Images work one of two ways, and that is the rule. Inline images travel inside the file and are referenced with a cid: URL, so they always render — this viewer decodes them to data URIs. Remote images are ordinary https:// URLs fetched when the message is opened, which is exactly why clients block them: that fetch is what tells the sender you opened it.
Why open a .eml here rather than in a mail client
Three reasons, all of which come up when the email is something you are reviewing rather than reading.
- 1
Nothing executes, nothing is fetched
The HTML is sanitized and rendered in a sandboxed frame with scripts off, so a suspicious message can be inspected without running anything — and without firing the tracking pixels a mail client would fetch on render.
- 2
You can change the conditions
Flip to a phone width, flip to a simulated dark-mode repaint, and see how the same file behaves. A mail client shows you exactly one set of conditions: its own.
- 3
No account for the file’s owner
Nothing is uploaded, so there is nothing to sign up for and nothing to delete afterwards. Close the tab and the file is gone.
How to export a .eml from your mail client
Every major client will hand you one, usually in two clicks or a drag.
Outlook (Windows or Mac)
File → Save As and choose .eml on newer builds, or drag the message straight out of the list onto your desktop, which writes a .eml file.
Apple Mail
Drag the message to your desktop, or File → Save As and pick “Raw Message Source”. Both give you a file this viewer reads.
Gmail
Open the message, use the ⋮ menu and choose “Download message”. Gmail writes the full MIME source, headers included.
Thunderbird
Right-click and choose “Save As”, or drag it to a folder. Thunderbird stores mail as MIME already, so the export is lossless.
Your ESP’s test send
Send yourself a test from Klaviyo, Mailchimp, HubSpot or Braze, then export the received message as .eml. This is the closest you get to what a subscriber received, merge tags and all.
A .eml is the most honest version of your email
Anything you preview inside an ESP has been rendered by that ESP. A .eml exported from a received test send is the message as it actually arrived: merge tags resolved, links rewritten by your click-tracking, the HTML mangled exactly as it was in transit. If a campaign looked fine in the editor and wrong in the inbox, the difference is in that file.
- Click-tracking redirects and rewritten links are visible as they were sent
- Merge tags appear resolved, so an unrendered {{first_name}} is obvious
- The HTML is the post-send version, including anything your ESP rewrote
When you need someone else to look at it
A local viewer is right for one person checking one file, and wrong the moment a second person is involved: no link to send, no way for them to point at the paragraph they mean, no record of who agreed to what. Upload the same .eml to Proofel and it becomes a proof with one shareable link — pinned comments, version compare, and every approval on the record.
- Upload a .eml directly — the same parser, server-side, with images kept
- One link for clients and colleagues, no reviewer accounts
- Version history, side-by-side compare, and an audit trail for every sign-off
More free email tools
Every one of these runs in your browser, needs no account, and has no usage limit.
.eml files, answered
- What is a .eml file?
- A .eml file is a single email saved in the standard MIME format described by RFC 5322 — the headers, the plain-text part, the HTML part, and any attachments or inline images, all in one text file. It is what mail clients write when you save or drag out a message, and it is the format almost every client can open.
- Why is a .eml file so much bigger than the email itself?
- Because everything in the file is text. Binary parts — a logo, a PDF — are base64-encoded, which makes a .eml roughly a third larger than the sum of its contents, and a message with three inline photos several megabytes. The upside is that you can open a .eml in any text editor and read the headers, including the Received chain every server added, straight off.
- How do I open a .eml file without Outlook?
- Drop it on this page. The file is parsed in your browser and the HTML part is rendered in a sandboxed frame, with inline cid: images resolved so the email looks like it did in the inbox. Nothing is uploaded and nothing is installed.
- Is it safe to open a .eml file here?
- Safer than opening it in a mail client, for two reasons. The email is sanitized and rendered in a sandboxed iframe with scripts disabled, so nothing in it can execute or reach the rest of the page. And the file never leaves your machine, so nothing is stored or transmitted. Note the flip side: because the frame is sandboxed, remote images may not load — which also means tracking pixels in the message are not fired.
- Why are some images missing?
- Inline images — the ones attached to the message and referenced with cid: — are resolved to data URIs and always appear. Images hosted on a remote server may be blocked by this page’s security policy, exactly as they are blocked by default in Outlook and for many Gmail users. If the message you are viewing is a real send, that blocked state is worth looking at: it is what a large share of recipients see.
- Can I see the headers and the raw source?
- This viewer shows the subject, the sender, and the rendered HTML body — the parts you need to judge how the email looks. It is not a forensic header analyser: if you are chasing a delivery path, the Received chain in the raw file read in a text editor, plus your own DMARC reports, is the right tool. Our deliverability check covers the domain-side records.
- Does it work on a phone?
- Yes, if you can get the file onto the phone. The picker accepts .eml from the Files app or a cloud drive, and the preview has its own mobile width so you can see how the email reflows.
- Can I share what I am looking at with someone else?
- Not from this viewer — it is entirely local, so there is nothing on a server to link to. That is deliberate. If you need someone else to look at the email and comment on it, that is what Proofel does: the same .eml becomes a proof with one review link, and reviewers never need an account.
Turn that .eml into something a client can approve
Upload the same file to Proofel and send one link: comments pinned to the pixel, version compare, and a sign-off on the record.
14-day all-access trial · no credit card required · reviewers never need an account