Dart

dependencies:
  http: ^1.1.0

# .env
KEPLERS_API_KEY=kms_your_api_key.live_...

import 'dart:convert';
import 'dart:io';
import 'package:http/http.dart' as http;

class KeplersEmailClient {
  final String apiKey;
  final String baseUrl;
  
  KeplersEmailClient({
    required this.apiKey,
    this.baseUrl = 'https://api.keplars.com',
  });

  Future<Map<String, dynamic>> sendEmail({
    required String to,
    required String subject,
    required String body,
    bool isHtml = false,
  }) async {
    return await _makeRequest('/api/v1/send-email/queue', {
      'to': [to],
      'subject': subject,
      'body': body,
      'is_html': isHtml,
    });
  }

  Future<Map<String, dynamic>> sendInstantEmail({
    required String to,
    required String subject,
    required String body,
    bool isHtml = false,
  }) async {
    return await _makeRequest('/api/v1/send-email/instant', {
      'to': [to],
      'subject': subject,
      'body': body,
      'is_html': isHtml,
    });
  }

  Future<Map<String, dynamic>> _makeRequest(String endpoint, Map<String, dynamic> data) async {
    try {
      final response = await http.post(
        Uri.parse('$baseUrl$endpoint'),
        headers: {
          'Authorization': 'Bearer $apiKey',
          'Content-Type': 'application/json',
        },
        body: jsonEncode(data),
      );
      
      if (response.statusCode == 200) {
        return jsonDecode(response.body);
      } else {
        throw Exception('Failed to send email: ${response.body}');
      }
    } catch (e) {
      throw Exception('Failed to send email: $e');
    }
  }
}

void main() async {
  final client = KeplersEmailClient(
    apiKey: Platform.environment['KEPLERS_API_KEY'] ?? '',
  );
  
  await sendWelcomeEmail(client, '[email protected]', 'John');
  await sendVerificationEmail(client, '[email protected]', '123456');
}

Future<void> sendWelcomeEmail(KeplersEmailClient client, String userEmail, String userName) async {
  try {
    final result = await client.sendEmail(
      to: userEmail,
      subject: 'Welcome $userName!',
      body: '<h1>Welcome $userName!</h1><p>Thank you for joining our platform.</p>',
      isHtml: true,
    );
    
    print('Email sent: $result');
  } catch (e) {
    print('Failed to send email: $e');
  }
}

Future<void> sendVerificationEmail(KeplersEmailClient client, String userEmail, String code) async {
  try {
    final result = await client.sendInstantEmail(
      to: userEmail,
      subject: 'Verify Your Email',
      body: 'Your verification code: $code',
      isHtml: false,
    );
    
    print('Verification email sent: $result');
  } catch (e) {
    print('Failed to send verification email: $e');
  }
}

class EmailService {
  static final _client = KeplersEmailClient(
    apiKey: const String.fromEnvironment('KEPLERS_API_KEY'),
  );

  static Future<bool> sendWelcomeEmail(String email, String name) async {
    try {
      await _client.sendEmail(
        to: email,
        subject: 'Welcome $name!',
        body: '<h1>Welcome $name!</h1>',
        isHtml: true,
      );
      return true;
    } catch (e) {
      print('Failed to send email: $e');
      return false;
    }
  }
}

class LoginScreen extends StatefulWidget {
  @override
  _LoginScreenState createState() => _LoginScreenState();
}

class _LoginScreenState extends State<LoginScreen> {
  final _emailController = TextEditingController();
  bool _isLoading = false;

  Future<void> _sendEmail() async {
    setState(() => _isLoading = true);
    
    final success = await EmailService.sendWelcomeEmail(
      _emailController.text,
      'User',
    );
    
    setState(() => _isLoading = false);
    
    ScaffoldMessenger.of(context).showSnackBar(
      SnackBar(
        content: Text(success ? 'Email sent!' : 'Failed to send email'),
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Padding(
        padding: EdgeInsets.all(16),
        child: Column(
          children: [
            TextField(
              controller: _emailController,
              decoration: InputDecoration(labelText: 'Email'),
            ),
            SizedBox(height: 20),
            ElevatedButton(
              onPressed: _isLoading ? null : _sendEmail,
              child: _isLoading 
                ? CircularProgressIndicator()
                : Text('Send Email'),
            ),
          ],
        ),
      ),
    );
  }
}

dependencies:
  mailer: ^6.0.1

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

class KeplersEmailSMTPClient {
  final String username;
  final String password;
  late final SmtpServer _smtpServer;

  KeplersEmailSMTPClient({
    required this.username,
    required this.password,
  }) {
    _smtpServer = SmtpServer(
      'smtp.keplars.com',
      port: 587,
      username: username,
      password: password,
    );
  }

  Future<bool> sendEmail({
    required String to,
    required String subject,
    required String body,
    bool isHtml = false,
  }) async {
    try {
      final message = Message()
        ..from = Address('[email protected]', 'Keplers Mail Service')
        ..recipients.add(to)
        ..subject = subject;

      if (isHtml) {
        message.html = body;
      } else {
        message.text = body;
      }

      final sendReport = await send(message, _smtpServer);
      return sendReport.sent.isNotEmpty;
    } catch (e) {
      print('SMTP Error: $e');
      return false;
    }
  }
}

void main() async {
  final smtpClient = KeplersEmailSMTPClient(
    username: Platform.environment['KEPLERS_SMTP_USERNAME'] ?? '',
    password: Platform.environment['KEPLERS_SMTP_PASSWORD'] ?? '',
  );
  
  await sendEmailViaSMTP(smtpClient, '[email protected]', 'Test Email', '<p>Hello World!</p>');
}

Future<void> sendEmailViaSMTP(
  KeplersEmailSMTPClient smtpClient,
  String userEmail,
  String subject,
  String body,
) async {
  final success = await smtpClient.sendEmail(
    to: userEmail,
    subject: subject,
    body: body,
    isHtml: true,
  );

  if (success) {
    print('SMTP email sent successfully');
  } else {
    print('SMTP send failed');
  }
}