('multipart(text/plain, application/pgp-signature)', 66),
('multipart(text/plain, text/html)', 8),
('multipart(text/plain, text/plain)', 4),
('multipart(text/plain)', 3),
('multipart(text/plain, application/octet-stream)', 2),
('multipart(text/plain, application/ms-tnef, text/plain)', 1),
('multipart(text/plain, multipart(text/plain, text/plain), multipart(multipart(text/plain, application/x-pkcs7-signature)))',
1),
('multipart(text/plain, multipart(text/plain))', 1),
('multipart(multipart(text/plain, text/plain, text/plain), application/pgp-signature)',
1),
('multipart(text/plain, video/mng)', 1),
('multipart(text/plain, application/x-java-applet)', 1),
('multipart(text/plain, application/x-pkcs7-signature)', 1),
('multipart(text/plain, multipart(text/plain, text/plain), text/rfc822-headers)',
1),
('multipart(text/plain, text/enriched)', 1)] テキスト形式が圧倒的
# 対してスパムメールは
structures_counter(spam_emails).most_common()
======================================================================
[('text/plain', 218),
('text/html', 183),
('multipart(text/plain, text/html)', 45),
('multipart(text/html)', 20),
('multipart(text/plain)', 19),
('multipart(multipart(text/html))', 5),
('multipart(text/plain, image/jpeg)', 3),
('multipart(text/html, application/octet-stream)', 2),
('multipart(multipart(text/html), application/octet-stream, image/jpeg)', 1),
('multipart(text/html, text/plain)', 1),
('multipart(multipart(text/plain, text/html), image/gif)', 1),
('multipart/alternative', 1),
('multipart(text/plain, application/octet-stream)', 1)] テキスト形式とHTML形式が同程度。明らかな違いが・・・。