Mail::SpamAssassin::Plugin::MIMEEval (3)

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NAME

Mail::SpamAssassin::Plugin::MIMEEval - perform MIME sanity tests of messages

SYNOPSIS

  loadplugin Mail::SpamAssassin::Plugin::MIMEEval

  body MULTIPART_ALT_NON_TEXT     eval:check_ma_non_text()

  body MIME_HTML_ONLY             eval:check_for_mime_html_only()
  describe MIME_HTML_ONLY         Message only has text/html MIME parts

DESCRIPTION

Utility functions for examining various encoded message components.

has_check_for_ascii_text_illegal

Adds capability check for ``if can()'' for check_for_ascii_text_illegal

check_for_ascii_text_illegal

If a

MIME

part claims to be text/plain or text/plain;charset=us-ascii and the Content-Transfer-Encoding is 7bit (either explicitly or by default), then we should enforce the actual text being only

TAB, NL, SPACE

through

TILDE,

i.e. all 7bit characters excluding NO-WS-CTL (per

RFC-2822

).

All mainstream

MTA

's get this right.

has_check_abundant_unicode_ratio

Adds capability check for ``if can()'' for check_abundant_unicode_ratio

check_abundant_unicode_ratio

A

MIME

part claiming to be text/plain and containing Unicode characters must be encoded as quoted-printable or base64, or use

UTF

data coding (typically with 8bit encoding). Any message in 7bit or 8bit encoding containing (

HTML

) Unicode entities will not render them as Unicode, but literally.

Thus a few such sequences might occur on a mailing list of developers discussing such characters, but a message with a high density of such characters is likely spam.

check_for_mime

Check for various

MIME

properties.

Use in rules such as:

  rawbody MIME_BASE64_BLANKS      eval:check_for_mime('mime_base64_blanks')
  describe MIME_BASE64_BLANKS     Extra blank lines in base64 encoding

  mime_base64_count
  mime_base64_encoded_text
  mime_body_html_count
  mime_body_text_count
  mime_faraway_charset
  mime_missing_boundary
  mime_multipart_alternative
  mime_multipart_ratio
  mime_qp_count
  mime_qp_long_line
  mime_qp_ratio
  mime_ascii_text_illegal
  mime_text_unicode_ratio

check_for_mime_html_only

Check for messages containing only text/html body parts

has_check_qp_ratio

Adds capability check for ``if can()'' for check_qp_ratio

check_qp_ratio

Takes a min ratio to use in eval to see if there is an spamminess to the ratio of quoted printable to total bytes in an email.