如何在 Postfix 上禁用 Sendgrid 邮件中继

Question

我有一个 Sendgrid 帐户，并已将 Sendgrid 设置为与我的 Postfix 邮件服务器配合使用。但是，我想禁用 Sendgrid 作为邮件中继。我按照本文进行设置：https://serverok.in/postfix-sendgrid

但是，我不确定如何禁用 Sendgrid。我是否只需要在 /etc/postfix/main.cf 中注释掉这些行？

 smtp_sasl_auth_enable = yes
 smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
 smtp_sasl_security_options = noanonymous
 smtp_sasl_tls_security_options = noanonymous
 smtp_tls_security_level = encrypt
 header_size_limit = 4096000
 relayhost = [smtp.sendgrid.net]:587

删除后，我应该只需重新启动 postfix 即可使用以下命令使更改生效？

 sudo postfix reload

这是我的 /etc/postfix/main.cf 文件：

  # See /usr/share/postfix/main.cf.dist for a commented, more complete version


  # Debian specific:  Specifying a file name will cause the first
  # line of that file to be used as the name.  The Debian default
  # is /etc/mailname.
  #myorigin = /etc/mailname

  smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
  biff = no

  # appending .domain is the MUA's job.
  append_dot_mydomain = no

  # Uncomment the next line to generate "delayed mail" warnings
  #delay_warning_time = 4h

  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

  # See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
  # information on enabling SSL in the smtp client.

  smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
  myhostname = [hidden for security]
  alias_maps = hash:/etc/aliases
  alias_database = hash:/etc/aliases
  mydestination = $myhostname, [hostname hidden], localhost.localdomain, , localhost
  relayhost =
  mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
  mailbox_size_limit = 0
  recipient_delimiter = +
  inet_interfaces = loopback-only
  inet_protocols = all

  transport_maps = hash:/etc/postfix/transport

  smtp_sasl_auth_enable = yes
  smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
  smtp_sasl_security_options = noanonymous
  smtp_sasl_tls_security_options = noanonymous
  smtp_tls_security_level = encrypt
  header_size_limit = 4096000
  relayhost = [smtp.sendgrid.net]:587

  smtpd_client_restrictions = reject_unknown_client
  disable_vrfy_command = yes

我希望能够禁用 Sendgrid 中继，但仍然让我的 postfix 邮件服务器正常运行并发送电子邮件。