Email technology checker
Upload an EML file to scan its headers, links, and HTML for signals from popular email platforms, delivery providers, analytics tools, and authentication systems.
Use free tool Free email tool
Open an EML file without installing another email app.
Drop in an EML or HTML file to inspect its headers, rendered email, source code, and available attachments directly in your browser.
- No signup
- Free to use
- A safe browser preview with headers and source
Free browser tool
EML viewer
The file is parsed locally. Its contents are not uploaded to Hypermatic.
Choose a file to begin.
Rendered email
Browser preview—not a native email-client testView email source
Attachments
How it works
From input to useful result in three steps.
- 1
Choose an EML or HTML file from your computer.
- 2
Review the sender, recipient, subject, date, and rendered message.
- 3
Inspect the source or download any attachments detected in the file.
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Questions
EML viewer FAQ
What is an EML file?
An EML file is a saved email message that can contain headers, plain text, HTML, and attachments in MIME format.
Are EML files uploaded anywhere?
No. This viewer reads and parses the selected file locally in your browser.
Is this an exact Outlook or Gmail preview?
No. It safely renders the message in a browser iframe. Native email clients have their own HTML and CSS rendering behavior, so use a dedicated email test for client-specific QA.
Free practical guide
How to open and inspect an EML file safely in a browser
An EML file is a saved email message containing transport headers, message bodies, and sometimes attachments. A local EML viewer is useful for inspecting a message without importing it into a mailbox, forwarding it to another service, or installing a desktop email client.
Quick answer
To open an EML file online without uploading it, choose the file in the viewer above. The browser parses the message locally and shows its headers, rendered HTML, source, and detected attachments. Treat the preview as an inspection aid rather than an exact Gmail or Outlook rendering test.
What is stored inside an EML file?
EML is a common file format for one email message. It normally starts with headers such as From, To, Subject, Date, Message-ID, and Content-Type. The body follows those headers and may be plain text, HTML, or a multipart MIME structure containing several alternatives and attachments.
Attachments are encoded into MIME parts with filenames and content types. HTML emails can also reference remote images that are not stored in the file. That distinction matters when an EML opens with missing artwork: the message may be intact while the remote asset is unavailable, blocked, or deliberately not loaded.
| View | What it helps you check |
|---|---|
| Headers | Sender, recipient, subject, date, routing, and authentication clues. |
| Rendered message | The readable HTML or plain-text body in a browser context. |
| Source | MIME boundaries, encodings, raw markup, and provider-added metadata. |
| Attachments | Embedded files detected in the MIME structure. |
Why use a local EML viewer?
Email files can contain personal correspondence, customer information, internal links, and identifiers. A browser-local viewer avoids sending that content to a remote conversion service. The file is selected from your device and processed in the current browser session.
Local processing does not make every attachment trustworthy. Do not open or run an unknown attachment simply because the EML itself was previewed safely. Apply the same security judgment you would use for an attachment received in your normal inbox.
How can an EML file help debug an email campaign?
The received EML shows what arrived after the sending platform and mail servers processed the campaign. Comparing it with the exported HTML can reveal rewritten tracking links, provider headers, added unsubscribe markup, changed character encoding, or MIME packaging problems.
Start with the visible symptom, then move down a layer. Check the rendered body for obvious content problems, inspect the HTML for malformed structure or missing inline styles, and review raw headers when the issue concerns sending infrastructure, authentication, or the platform used to deliver the message.
- Save the original received message rather than copying its rendered body.
- Compare both HTML and plain-text MIME parts when content differs.
- Look for Content-Transfer-Encoding when characters appear corrupted.
- Keep the EML as evidence when escalating a delivery or rendering issue.
Is an EML browser preview the same as Gmail or Outlook?
No. A browser uses a modern web rendering engine, while email clients apply their own HTML sanitization, CSS support, image policies, and security rules. Desktop Outlook can behave very differently from Gmail, Apple Mail, and browser-based previews even when they all open the same message.
Use this free EML viewer to understand the file and perform fast inspection. Use real-client testing when the question is whether a layout, responsive breakpoint, dark mode treatment, or interactive element works in a specific email client.
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