Message Lint

Message Lint is an RFC 5322/MIME/DSN/MDN/Tracking-Status message validator.

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What does Message Lint check for?

  • Syntax errors in headers, including RFC 5322 headers, MIME headers,
    Delivery Status Notification headers (RFC 3461), Message
    Disposition Notification headers (RFC 3798) and several other standards-track
    header fields.
  • Use of RFC 5322 comments or whitespace in places likely to cause problems.
  • Other RFC 5322 syntax which is obsolete, deprecated or likely to cause problems.
  • Use of non-standard header fields.
  • Use of restricted-use header fields (e.g. RFC 2156 headers).
  • Use of unregistered tokens in header fields.
  • Invalid domain name or MIME-boundary characters.
  • Duplicate Headers.
  • Mandatory Headers.
  • Inconsistent use of content-transfer-encoding, charsets and body text with respect to 8-bit characters.
  • Incorrect use of quoted-printable, including warnings for unnecessary use and line-length restrictions.
  • Incorrect use of base64, including line-length restrictions.
  • Validates Content-MD5 header values (RFC 1864)
  • Unfamiliar character set names
  • Verifies text parts only use legal characters if the character set is US-ASCII, ISO-8859-*, or UTF-8.
  • Header or text/plain lines which are too long.
  • Missing end boundaries on multipart objects
  • Misspellings of application/octet-stream.
  • Mismatch between multipart/report "report-type" param and inner report type.
  • Some news header support (RFC 1036).