public void setHostPort(final String hostPort) {
        this.hostPort = hostPort;
    }
Sets the name of the remote MTA for informative purposes. Default is
host:port, where host and port are the values which were used to open the TCP
connection to the server, as they were passed to the connect method.
src/test/java/de/gessnerfl/fakesmtp/smtp/client/SMTPClient.java