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EML & MIME Email Analyzer

Open an EML message locally, decode MIME headers and transfer encodings, inspect the nested part tree, and preview or download attachments without contacting remote resources.

Inspect an EML message

Paste raw RFC 5322 source or choose an .eml file. HTML stays source-only, attachments use passive previews, and no address or remote resource in the message is requested.

Email analysis

Message fields, decoded MIME parts, attachments, delivery headers, and passive previews will appear here.

Read the message structure without opening the email

DecodeLens unfolds RFC 5322 headers, decodes RFC 2047 display text and RFC 2231 filenames, builds the nested MIME tree, and opens Base64 or quoted-printable parts as local bytes. Attachments can use the same passive file preview system as other DecodeLens tools.

Analysis boundaries

  • HTML mail is never rendered as an active page. Remote images, links, forms, scripts, and tracking resources are not loaded.
  • Authentication-Results, Received, DKIM-Signature, and ARC fields are inspected as message data. DNS lookups and cryptographic DKIM verification are not performed.
  • Common RFC 2047 headers, RFC 2231 parameters, Base64, quoted-printable, 7bit, 8bit, binary, nested multipart, and attached message structures are supported within central limits.
  • A malformed message can be decoded conservatively, but its displayed routing or identity fields are not proof of sender authenticity.

Related tools for this workflow

Continue with tools that decode, convert, inspect, or verify the same data.

Inspect headers, MIME layers, and attachments together

Load the example to follow a multipart/mixed message into multipart/alternative text and HTML bodies, then open the transfer-decoded JSON attachment in the shared preview.

EML input

RFC 5322 headers + multipart MIME body

Structured result

decoded headers + MIME tree + passive attachment preview

EML and MIME Analyzer FAQ

Does opening an EML file contact the sender or load tracking pixels?

No. The message is parsed in a browser worker. HTML remains source text and remote URLs are not requested.

Does dkim=pass mean DecodeLens verified the signature?

No. That value is an Authentication-Results claim written by another mail system. Independent DKIM verification requires the signed header set, canonicalization, DNS key retrieval, and cryptographic checks.

Can I download a decoded attachment?

Yes. Select an attachment to decode its MIME transfer encoding, inspect the detected file type, and download the resulting local bytes.