code: public SMailPostalMotorbike useSsl() {
          if (!hasAuth) {
              throw new IllegalStateException("Not found the authenticator for SSL: session=" + session);
          }
          if (MotorbikeSecurityType.STARTTLS.equals(securityType)) {
              throw new IllegalStateException("Cannot use SSL with STARTTLS: session=" + session);
          }
          securityType = MotorbikeSecurityType.SSL;
          registerTransportProtocol("smtps");
          registerSmtpAuth();
          return this;
      }
docs: Motorbike uses SMTP over SSL. <br>
  It needs authenticator, that you can specify by constructor.
  <pre>
  e.g.
  SMailPostalMotorbike motorbike = new SMailPostalMotorbike("sea", "land").<span style="color: #CC4747">useSsl()</span>;
  motorbike.registerConnectionInfo(...);
  motorbike.registerReturnPath(...);
  </pre>
  @return this. (NotNull)