这里是main.cf中的TLS选项：
# TLS parameters smtpd_tls_cert_file=/etc/ssl/certs/cert.pem smtpd_tls_key_file=/etc/ssl/private/cert.key smtpd_use_tls = yes smtpd_tls_security_level = may smtpd_tls_CApath = /etc/ssl/certs smtp_tls_security_level = may smtp_tls_CApath = /etc/ssl/certs smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3 smtpd_tls_mandatory_ciphers = high tls_high_cipherlist = EDH+CAMELLIA:EDH+aRSA:EECDH+aRSA+AESGCM:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH:+CAMELLIA256:+AES256:+CAMELLIA128:+AES128:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!DSS:!RC4:!SEED:!ECDSA:CAMELLIA256-SHA:AES256-SHA:CAMELLIA128-SHA:AES128-SHA smtp_tls_loglevel = 1 smtpd_tls_loglevel = 1 smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache 这里是来自mail.log的示例日志：
Feb 24 21:06:05 myserver postfix/smtpd[31346]: Anonymous TLS connection established from mail-yw0-f170.google.com[209.85.161.170]: TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits) Feb 24 21:10:07 myserver postfix/smtpd[31289]: Anonymous TLS connection established from mail-wr0-f179.google.com[209.85.128.179]: TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits) Feb 24 21:14:48 myserver postfix/smtpd[31346]: Anonymous TLS connection established from mail-oi0-f48.google.com[209.85.218.48]: TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)
这里是telnet输出：
telnet myserver 25 Trying XXX.XXX.XXX.XXX... Connected to myserver. Escape character is '^]'. 220 myserver ESMTP Postfix ehlo domain 250-myserver 250-PIPELINING 250-SIZE 36800000 250-VRFY 250-ETRN 250-STARTTLS 250-ENHANCEDSTATUSCODES 250-8BITMIME 250 DSN STARTTLS 220 2.0.0 Ready to start TLS
TestReceiver从checktls.com：
CheckTLS Confidence Factor for "adress@myserver": 100 MXServer Pref Connect Allowed CanUse TLSAdv CertOK TLSNeg SndrOK RcvrOK 20 OK OK OK OK OK OK OK OK Average 100% 100% 100% 100% 100% 100% 100% 100%
但是，当我必须在Gmail中创build邮件仍然我看到红色的挂锁。 哪里不对？
更新：
以下是来自gmail的消息中的标题：
Received: from mail-oi0-f47.google.com (mail-oi0-f47.google.com [209.85.218.47]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by myserver (Postfix) with ESMTPS id 30B65866EDB for <address@myserver>; Sun, 26 Feb 2017 14:57:36 +0100 (CET)
这表明TLS正在工作？ 为什么我仍然看到红色的挂锁？ 我还可以做些什么？
红色挂锁表示邮件未经encryption发送。 您可以通过在main.cf（证书，私钥）中configuration您的tls设置来启用encryption。
如果你已经configuration了这些，只需添加这些参数（注意它是smtp，而不是smtpd）：
smtp_use_tls = yes smtp_tls_security_level = may