WiFi in networkd

nano /etc/wpa_supplicant/wpa_supplicant-wlo1.conf
ctrl_interface=/run/wpa_supplicant
update_config=1
 
 
network={
        ssid="My SSID"
        psk=4a11d6d1d48bd83ae9f0dc4f804dddc60a91782653fc883c0b9f23c8a2db72ef
}
systemctl enable wpa_supplicant@wlo1.service

Enable networkd in Debian 9

mv /etc/network/interfaces /etc/network/interfaces.save
systemctl enable systemd-networkd
nano /etc/systemd/network/lan0.network
[Match]
Name=enp0s3
 
[Network]
DHCP=yes
 
[DHCP]
ClientIdentifier=mac
systemctl start systemd-networkd

Mail Server

amavisd-new genrsa /var/lib/dkim/domain.pem 1024
 
chown amavis:amavis /var/lib/dkim/domain.pem
 
chmod 0400 /var/lib/dkim/domain.pem
 
nano /etc/amavis/conf.d/50-user
 
dkim_key("domain", "dkim", "/var/lib/dkim/domain.pem");
 
"domain"  => { d => "domain", a => 'rsa-sha256', ttl => 10*24*3600 },
 
systemctl restart amavis
 
amavisd-new showkeys
 
amavisd-new testkeys