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.IX Title "Mail::SpamAssassin::Message::Metadata 3pm"
.TH Mail::SpamAssassin::Message::Metadata 3pm "2020-01-31" "perl v5.28.1" "User Contributed Perl Documentation"
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.SH "NAME"
Mail::SpamAssassin::Message::Metadata \- extract metadata from a message
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This class is tasked with extracting \*(L"metadata\*(R" from messages for use as
Bayes tokens, fodder for eval tests, or other rules.  Metadata is
supplemental data inferred from the message, like the examples below.
.PP
It is held in two forms:
.PP
1. as name-value pairs of strings, presented in mail header format.  For
  example, \*(L"X\-Languages\*(R" => \*(L"en\*(R".  This is the general form for simple
  metadata that's useful as Bayes tokens, can be added to marked-up
  messages using \*(L"add_header\*(R", etc., such as the trusted-relay inference
  and language detection.
.PP
2. as more complex data structures on the \f(CW$msg\fR\->{metadata} object.  This
  is the form used for metadata like the \s-1HTML\s0 parse data, which is stored
  there for access by eval rule code.   Because it's not simple strings,
  it's not added as a Bayes token by default (Bayes needs simple strings).
.SH "PUBLIC METHODS"
.IX Header "PUBLIC METHODS"
.IP "\fBnew()\fR" 4
.IX Item "new()"