Yes, I had sent the messages to myself, so I found the problem.
The header from yahoo mail server to my server shows: Message-ID: <1986254504.2695776.147946658...@mail.yahoo.com> Subject: linoookk MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: base64 The header from my server to yahoo mail server did not shows "Content-Transfer-Encoding: base64", and just shows "cipher ECDHE-RSA-AES128-GCM-SHA256". The mail log shows no errors. The log level is set to 1. ---- On 星期五, 18 十一月 2016 19:57:04 -0800<li...@lazygranch.com> wrote ---- My advice would be to send a test message to a yahoo account you own. Then reply to yourself. Read the headers and the maillog. Something useful should indicating the problem should pop up. You may have to change a log level in one of the postfix cf files. From: vod vos Sent: Friday, November 18, 2016 7:05 PM To: postfix-users Subject: How to encrypt the mail content? Hi, I have configured the TLS, when I receive the mail such as yahoo mail, the mail content is transferred encoding like base64. When I send mail to yahoo account or others, the content is clear text, how to encrypt the content in an acceptable encoding to other mail servers? Thanks.
