To: test@example.com From: test@example.com Subject: ISO-2022-JP and 7bit containing =67 and hence looking like quoted-printable Message-ID: <10a2aa17-e92f-417c-864e-575d4e371702@example.com> Date: Tue, 3 Apr 2018 19:09:16 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 Content-Type: text/plain; charset=SHIFT-JIS; format=flowed Content-Language: ja-JP Content-Transfer-Encoding: 7bit Œ»‹µ