RFC 5322 EML Viewer
Parse and view EML email files directly in your browser. Extract headers, decode MIME multipart content, view plain text and HTML bodies, and download attachments. Supports RFC 5322 message format, RFC 2047 encoded headers, and MIME content-transfer encodings. All processing runs locally for complete privacy.
EML File Viewer
Load an .eml file or paste raw email source to parse and view the message.
Email Headers
Show all headers
Message Body
Attachments
How It Works
EML files follow RFC 5322 (Internet Message Format), which defines the standard structure of email messages. Every email consists of a header section and a body section, separated by a blank line. The header section contains structured fields like From, To, Subject, and Date, while the body contains the message content.
For emails with rich content, MIME (Multipurpose Internet Mail Extensions, defined in RFCs 2045-2049) extends the basic format to support multipart messages, attachments, and non-ASCII text. Multipart messages use boundary strings to separate different content sections such as plain text, HTML, and file attachments.
This parser extracts all headers, decodes RFC 2047 encoded words (for internationalized headers), processes MIME multipart boundaries recursively, decodes Base64 and Quoted-Printable content-transfer encodings, and reconstructs the email for viewing. Attachments are decoded and made available for download as blob URLs.
Common Use Cases
- Inspecting email headers for debugging delivery issues — Examine Received headers, SPF/DKIM results, and routing information to diagnose why emails are delayed or rejected.
- Viewing exported emails without an email client — Open .eml files saved from Outlook, Thunderbird, or Gmail without needing to install an email application.
- Analyzing email structure for development and testing — Verify that emails generated by your application have correct MIME structure, headers, and encoding.
- Extracting attachments from .eml files — Download attached files from exported email messages without importing them into an email client.
- Forensic analysis of email messages — Inspect raw email sources to verify sender authenticity, trace message routing, and detect spoofing attempts.
Frequently Asked Questions
What is an EML file?
An EML file is a plain-text file that stores a single email message in the format defined by RFC 5322. It contains the full email including headers (From, To, Subject, Date, etc.), the message body, and any attachments encoded using MIME. Most email clients such as Outlook, Thunderbird, and Apple Mail can export and import messages as .eml files.
What is RFC 5322?
RFC 5322 (Internet Message Format) is the Internet standard that defines the syntax for email messages. It specifies how headers are structured, how the message body is separated from headers using a blank line, header folding rules for long values, and the overall text format that all email systems use to create and interpret messages. It supersedes the earlier RFC 2822 and RFC 822.
Can I view HTML emails safely?
Yes. This tool renders HTML email content inside a sandboxed iframe with restricted permissions. External resources like images, scripts, and tracking pixels are blocked from loading. The sandbox prevents any JavaScript execution and restricts navigation, so you can safely preview the HTML layout of an email without security risks.
Are my emails secure when using this tool?
Yes. All parsing and rendering happens entirely in your browser using JavaScript. Your email data is never uploaded to any server. No data leaves your machine, ensuring complete privacy for sensitive email content. You can even use this tool offline once the page has loaded.