Somewhat off topic, but whenever you have multiple arrays that describe the same thing, you should probably make it a hash of hashes instead. Something like this would be better and easier to deal with:

%messages = (1 => { unixfrom        => "blah",
                    return_path     => "foo@bar.com",
                    received        => "blorg",
                    date            => "another date",
                    from            => "bar@foo.com",
                    to              => "you@me.com",
                    subject         => "Spam Me Senseless!",
                    message_id      => 42,
                    mimeversion     => "text/plain",
                    content_type    => "text/plain",
                    xstatus         => "foop",
                    xkeywords       => "spam trash garbage",
                    xuid            => 13
                  }
             );
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With a hash, the key represents the message and could either be any unique value, or possibly even the message_id (if it is unique). Printing it out is then just a matter of looping through the keys, retrieving the values, and printing them.