服务器怎么搭建邮件服务器

# 设置完全限定域名（FQDN）
sudo hostnamectl set-hostname mail.example.com

# 确认 /etc/hosts 中主机名与 IP 对应
sudo tee -a /etc/hosts <<'EOF'
203.0.113.10 mail.example.com mail
EOF

# 验证：hostname -f 必须输出 mail.example.com
hostname -f

sudo useradd -m -s /usr/sbin/nologin admin
sudo passwd admin           # 设置邮箱密码

# 生成 Dovecot 可用的密码哈希（可选，用于数据库认证场景）
doveadm pw -s SHA512-CRYPT

sudo apt update
sudo apt install -y postfix postfix-pcre mailutils

sudo tee -a /etc/postfix/main.cf <<'EOF'
# --- 身份标识 ---
myhostname = mail.example.com
mydomain = example.com
myorigin = $mydomain
mydestination = $myhostname, $mydomain, localhost
inet_interfaces = all
inet_protocols = all

# --- 邮箱格式 ---
home_mailbox = Maildir/
mailbox_size_limit = 0
message_size_limit = 52428800

# --- 客户端提交认证（交给 Dovecot 的 SASL）---
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_auth_enable = yes
smtpd_sasl_security_options = noanonymous
smtpd_tls_auth_only = yes

# --- TLS 证书（用 Let's Encrypt 签发的证书）---
smtpd_tls_cert_file = /etc/letsencrypt/live/mail.example.com/fullchain.pem
smtpd_tls_key_file = /etc/letsencrypt/live/mail.example.com/privkey.pem
smtpd_tls_security_level = may
smtp_tls_security_level = may
smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1
smtpd_tls_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1

# --- 收件限制，防止被当成开放中继 ---
smtpd_recipient_restrictions =
    permit_mynetworks,
    permit_sasl_authenticated,
    reject_unauth_destination,
    reject_rbl_client zen.spamhaus.org
EOF

sudo tee -a /etc/postfix/master.cf <<'EOF'
submission inet n       -       y       -       -       smtpd
  -o syslog_name=postfix/submission
  -o smtpd_tls_security_level=encrypt
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_client_restrictions=permit_sasl_authenticated,reject

smtps     inet  n       -       y       -       -       smtpd
  -o syslog_name=postfix/smtps
  -o smtpd_tls_wrappermode=yes
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_client_restrictions=permit_sasl_authenticated,reject
EOF

sudo postfix check && sudo systemctl restart postfix

sudo apt install -y dovecot-core dovecot-imapd dovecot-pop3d dovecot-lmtpd

# 1) 启用协议
sudo sed -i 's/^#protocols = .*/protocols = imap pop3 lmtp/' /etc/dovecot/dovecot.conf

# 2) 邮箱存储格式与位置，必须与 main.cf 的 home_mailbox 一致
sudo tee /etc/dovecot/conf.d/10-mail.conf <<'EOF'
mail_location = maildir:~/Maildir
mail_privileged_group = mail
EOF

# 3) 认证方式：启用明文机制但强制走 TLS
sudo tee /etc/dovecot/conf.d/10-auth.conf <<'EOF'
disable_plaintext_auth = yes
auth_mechanisms = plain login
!include auth-system.conf.ext
EOF

# 4) 为 Postfix 暴露 SASL 套接字
sudo tee /etc/dovecot/conf.d/10-master.conf <<'EOF'
service auth {
  unix_listener /var/spool/postfix/private/auth {
    mode = 0660
    user = postfix
    group = postfix
  }
}
EOF

sudo tee /etc/dovecot/conf.d/10-ssl.conf <<'EOF'
ssl = required
ssl_cert =