Provided by: spamassassin_3.4.4-1ubuntu1_all bug


       Mail::SpamAssassin::Message::Metadata - extract metadata from a message


       This class is tasked with extracting "metadata" 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.

       It is held in two forms:

       1. as name-value pairs of strings, presented in mail header format.  For
         example, "X-Languages" => "en".  This is the general form for simple
         metadata that's useful as Bayes tokens, can be added to marked-up
         messages using "add_header", etc., such as the trusted-relay inference
         and language detection.

       2. as more complex data structures on the $msg->{metadata} object.  This
         is the form used for metadata like the HTML 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).