To add the capability of sending email from any host I decided to install msmtp-mta on any host that does not include a full email server. The config is done in the file: /etc/msmtprc
and here is the contents:
account default
host cubietruck.steppenwolf.de
auto_from on
maildomain steppenwolf.de
tls on
tls_trust_file /etc/CA/cert.pem