gentoo-overlay/mail-mta/postfix/files/postfix.service

[Unit]
Description=Postfix Mail Transport Agent
After=network.target

[Service]
Type=forking
ExecStartPre=-/usr/bin/newaliases
ExecStart=/usr/sbin/postfix start
ExecStop=/usr/sbin/postfix stop
ExecReload=/usr/sbin/postfix reload
# Hardening
PrivateTmp=yes
PrivateDevices=yes
ProtectSystem=full
ReadWritePaths=-/etc/mail/aliases.db
CapabilityBoundingSet=~ CAP_NET_ADMIN CAP_SYS_ADMIN CAP_SYS_BOOT CAP_SYS_MODULE
MemoryDenyWriteExecute=true
ProtectKernelModules=true
ProtectKernelTunables=true
ProtectControlGroups=true
RestrictAddressFamilies=AF_INET AF_INET6 AF_NETLINK AF_UNIX
RestrictNamespaces=true
RestrictRealtime=true

[Install]
WantedBy=multi-user.target