code: private boolean isPropertiesSet() {
          return !this.host.isEmpty() &&
                  this.port > 0 &&
                  !this.username.isEmpty() &&
                  !this.password.isEmpty() &&
                  !this.toAdd.isEmpty() &&
                  !this.fromAdd.isEmpty() &&
                  !this.subject.isEmpty() &&
                  !this.msg.isEmpty() &&
                  this.attachments != null && this.attachments.length > 0;
      }
docs: This will check if the necessary properties
  are set for sending an email successfully
  @return boolean