sudo apt update && sudo apt upgrade -y。/etc/apt/sources.list后，執行sudo apt update && sudo apt dist-upgrade -y，重啟系統。sudo systemctl start/stop/restart postfix dovecot。sudo systemctl status postfix dovecot。/etc/postfix/main.cf和/etc/dovecot/dovecot.conf，啟用SASL認證、限制郵件轉發等。sudo apt update && sudo apt full-upgrade，安裝安全補丁。journalctl或logwatch監控日志，分析異常。參考來源：[1,2,3,4,5,6,7,8,9,10]
