如何在flutter上从用户向管理员发送电子邮件？

import 'package:mailer/mailer.dart';
import 'package:mailer/smtp_server.dart';

void sendEmail() async {
  String username = 'your_email@example.com'; // 发送者邮箱
  String password = 'your_password'; // 发送者邮箱密码

  final smtpServer = SmtpServer('smtp.exmail.qq.com',
      username: username,
      password: password,
      port: 465,
      ssl: true);

  final message = Message()
    ..from = Address(username, 'Your Name') // 发送者姓名
    ..recipients.add('admin@example.com') // 接收者邮箱
    ..subject = 'Flutter Email Test' // 邮件主题
    ..text = 'This is a test email from Flutter.'; // 邮件正文

  try {
    final sendReport = await send(message, smtpServer);
    print('Message sent: ${sendReport.toString()}');
  } catch (e) {
    print('Error occurred: $e');
  }
}