For TLS, keys are generated using https://github.com/cloudflare/cfssl
These private keys are published online, don't use them for anything other than local testing.

Commands:

# Generate CA
cfssl genkey -initca cfssl-ca-csr.json | cfssljson -bare ca

echo '{}' | cfssl gencert -ca ca.pem -ca-key ca-key.pem -hostname moxmail1.mox1.example - | cfssljson -bare moxmail1
echo '{}' | cfssl gencert -ca ca.pem -ca-key ca-key.pem -hostname moxmail2.mox2.example - | cfssljson -bare moxmail2
echo '{}' | cfssl gencert -ca ca.pem -ca-key ca-key.pem -hostname moxmail3.mox3.example - | cfssljson -bare moxmail3
echo '{}' | cfssl gencert -ca ca.pem -ca-key ca-key.pem -hostname postfixmail.postfix.example - | cfssljson -bare postfixmail