我的服务器运行在 Ubuntu 14.04 上，并且安装了 Postfix。当我向我的 gmail 帐户发送邮件时，邮件会被归类为垃圾邮件。我设置了 SPF、DKIM 和 DMARC，以下是确认信息：
Authentication-Results: mx.google.com;
dkim=pass [email protected];
spf=pass (google.com: domain of [email protected] designates xxx.xxx.xx.xxx as permitted sender) [email protected];
dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=mydomain.com
但有一把红色的挂锁上写着：encryption: mydomain.com did not encrypt this message。
别人发来的邮件有这样的说明：encryption: Standard (TLS)
你能帮我一下吗？我该怎么办？这可能是我服务器发送的电子邮件被归为垃圾邮件的原因吗？提前致谢。
我的/etc/postfix/main.cf：
biff = no
append_dot_mydomain = no
readme_directory = no
# TLS parameters
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = mail.mydomain.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = mydomain.com, bociuch, localhost.localdomain, localhost
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_command = procmail -a "$EXTENSION"
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all
milter_protocol = 2
milter_default_action = accept
smtpd_milters = inet:localhost:12301
non_smtpd_milters = inet:localhost:12301
答案1
你缺少了smtp_tls_security_level指示。
smtp_tls_security_level = may
这会将其设置为机会性 TLS，如果服务器支持，则使用加密连接，但如果服务器不支持，则允许未加密的连接。
smtp_tls_security_level的默认值为none。