Repository: flutter
Issue: [flutter_markdown] Any link label containing '@' is assumed to have a destination using :mailto
Labels: package,team-ecosystem,has reproducible steps,P3,p: flutter_markdown,found in release: 3.10,triaged-ecosystem,found in release: 3.13

### Is there an existing issue for this?

- [X] I have searched the [existing issues](https://github.com/flutter/flutter/issues)
- [X] I have read the [guide to filing a bug](https://flutter.dev/docs/resources/bug-reports)

### Steps to reproduce

1. Create a new flutter app and install packages `flutter_markdown` and `url_launcher`
2. Change `main.dart` to display a clickable markdown link containing an '@' character like \[!android@lemmy.world\]\(https://lemmy.world/c/android)
3. Run the app and click the link on the page

### Expected results

On click, [https://lemmy.world/c/android](https://lemmy.world/c/android) should be opened

### Actual results

The link doesn't open. It seems to get parsed as an email address.

### Code sample

<details><summary>Code sample</summary>

```dart
import 'package:flutter/material.dart';
import 'package:flutter_markdown/flutter_markdown.dart';
import 'package:url_launcher/url_launcher.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: Text(widget.title),
      ),
      body: Center(
        child: MarkdownBody(
            data: '[!android@lemmy.world](https://lemmy.world/c/android)',
            onTapLink: (text, href, title) async {
              var url = Uri.parse(href!);
              if (await canLaunchUrl(url)) {
                await launchUrl(url);
              } else {
                throw 'Could not launch $href';
              }
            },
        )
      )
    );
  }
}
```

</details>


### Screenshots or Video

<details>
<summary>Screenshots / Video demonstration</summary>

[Upload media here]

</details>


### Logs

<details><summary>Logs</summary>

```console
[VERBOSE-2:dart_vm_initializer.cc(41)] Unhandled Exception: Could not launch mailto:android@lemmy.world
#0      _MyHomePageState.build.<anonymous closure> (package:bug_report/main.dart:58:17)
<asynchronous suspension>
```

</details>


### Flutter Doctor output

<details><summary>Doctor output</summary>

```console
flutter doctor -v
[✓] Flutter (Channel stable, 3.10.6, on macOS 13.4.1 22F770820d darwin-arm64, locale en-US)
    • Flutter version 3.10.6 on channel stable at /Users/nickwarriner/Programs/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision f468f3366c (5 days ago), 2023-07-12 15:19:05 -0700
    • Engine revision cdbeda788a
    • Dart version 3.0.6
    • DevTools version 2.23.1

[✓] Android toolchain - develop for Android devices (Android SDK version 32.1.0-rc1)
    • Android SDK at /Users/nickwarriner/Library/Android/sdk
    • Platform android-33, build-tools 32.1.0-rc1
    • Java binary at: /Users/nickwarriner/Library/Application Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/222.4459.24.2221.9971841/Android
      Studio.app/Contents/jbr/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 17.0.6+0-17.0.6b802.4-9586694)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 14.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 14E222b
    • CocoaPods version 1.11.3

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2022.2)
    • Android Studio at /Users/nickwarriner/Library/Application Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/222.4459.24.2221.9971841/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.6+0-17.0.6b802.4-9586694)

[✓] Android Studio (version 2022.2)
    • Android Studio at /Users/nickwarriner/Library/Application Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/222.4459.24.2221.10121639/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.6+0-17.0.6b802.4-9586694)

[✓] IntelliJ IDEA Ultimate Edition (version 2022.1.4)
    • IntelliJ at /Applications/IntelliJ IDEA.app
    • Flutter plugin version 74.0.1
    • Dart plugin version 221.6103.1

[✓] IntelliJ IDEA Ultimate Edition (version 2023.1.3)
    • IntelliJ at /Users/nickwarriner/Applications/JetBrains Toolbox/IntelliJ IDEA Ultimate.app
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart

[✓] IntelliJ IDEA Ultimate Edition (version 2023.1.2)
    • IntelliJ at /Users/nickwarriner/Library/Application Support/JetBrains/Toolbox/apps/IDEA-U/ch-0/231.9011.34/IntelliJ IDEA.app
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart

[✓] IntelliJ IDEA Ultimate Edition (version 2023.1.3)
    • IntelliJ at /Users/nickwarriner/Library/Application Support/JetBrains/Toolbox/apps/IDEA-U/ch-0/231.9161.38/IntelliJ IDEA.app
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart

[✓] VS Code (version 1.80.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.68.0

[✓] Connected device (3 available)
    • iPhone 14 Pro Max (mobile) • 5DAFCF04-2C22-496C-B250-9A8E5E779191 • ios            • com.apple.CoreSimulator.SimRuntime.iOS-16-4 (simulator)
    • macOS (desktop)            • macos                                • darwin-arm64   • macOS 13.4.1 22F770820d darwin-arm64
    • Chrome (web)               • chrome                               • web-javascript • Google Chrome 114.0.5735.198

[✓] Network resources
    • All expected network resources are available.

• No issues found!

```

</details>