dart_mail 1.0.0

A pure Dart email stack featuring SMTP and IMAP servers, DNS MX resolution, and email relay support.

dart_mail

dart_mail is a pure Dart email stack implementing SMTP, IMAP, DNS MX resolution, and email delivery.

It allows you to build a complete mail server or mail-enabled application using Dart only — no external mail services required.

---

Overview

dart_mail provides:

• 📤 SMTP server for receiving and relaying email
• 📥 IMAP server for mailbox access
• 🌐 DNS MX resolution for remote delivery
• 🗂️ Pluggable mailbox storage
• 🔐 Authentication abstraction
• 🔁 SMTP relay client for outbound delivery

Designed for servers, self-hosted solutions, testing environments, and embedded email infrastructure.

Add this note section to the README (fits best after Overview or Requirements):

---

Cross-Platform

dart_mail runs on any operating system supported by Dart:

• Linux
• macOS
• Windows
• Docker
• Cloud runtimes

It has no dependency on Linux-specific architectures or system services, unlike traditional SMTP/IMAP servers (Postfix, Exim, Dovecot, Sendmail).

This makes dart_mail ideal for:

• Cross-platform development
• Local testing on macOS or Windows
• Containerized and embedded deployments
• Environments where installing or managing system mail servers is not desirable

All networking, TLS, DNS resolution, and protocol handling are implemented entirely in Dart.

---

Features

• ✉️ Fully functional SMTP server

  • Authentication
  • Local delivery
  • Remote relay via MX lookup

• 📬 IMAP & IMAPS servers

  • STARTTLS and TLS support

• 🌍 DNS-over-HTTPS MX resolution

• 🔐 Pluggable authentication providers

• 🗄️ Swappable mailbox storage backends

• 🧪 Ideal for development, testing, and self-hosted setups

• ⚡ 100% Dart, no native dependencies

---

Minimal Example

A complete SMTP + IMAP server using in-memory storage:

import 'dart:io';

import 'package:dart_mail/dns_resolver.dart';
import 'package:dart_mail/email_delivery_client.dart';
import 'package:dart_mail/imap_server.dart';
import 'package:dart_mail/smtp_server.dart';

void main() async {
  // Simple in-memory authentication
  final authProvider = MapAuthProvider({
    '[e-mail]': 'password123',
    '[e-mail]': 'secret',
  });

  // Shared mailbox storage
  final mailboxStore = InMemoryMailboxStore(authProvider);

  // DNS resolver for MX lookups
  final dnsResolver = DNSOverHttpsResolver.google();

  // SMTP client for relaying external emails
  final emailDeliveryClient = SMTPEmailDeliveryClient(
    hostname: 'localhost',
    dnsResolver: dnsResolver,
  );

  // TLS configuration
  final securityContext = SecurityContext()
    ..useCertificateChain('certs/localhost.pem')
    ..usePrivateKey('certs/localhost.key');

  // Start SMTP server
  final smtpServer = SMTPServer(
    hostname: '0.0.0.0',
    port: 2525,
    securityContext: securityContext,
    authProvider: authProvider,
    mailboxStore: mailboxStore,
    dnsResolver: dnsResolver,
    emailDeliveryClient: emailDeliveryClient,
  );

  // Start IMAP / IMAPS server
  final imapServer = IMAPServer(
    hostname: '0.0.0.0',
    mailboxStore: mailboxStore,
    authProvider: authProvider,
    securityContext: securityContext,
    imapPort: 1143,
    imapsPort: 1993,
  );

  await smtpServer.start();
  await imapServer.start();

  print('SMTP: 2525');
  print('IMAP: 1143 (STARTTLS)');
  print('IMAPS: 1993');

  // Graceful shutdown
  ProcessSignal.sigint.watch().listen((_) async {
    await smtpServer.close();
    await imapServer.close();
    exit(0);
  });
}

---

Architecture

SMTP Client
   │
   ▼
SMTP Server ──► MailboxStore ◄── IMAP Server
   │
   └──► SMTP Relay ──► Remote MX Server

• SMTP writes messages
• IMAP reads messages
• MailboxStore is the shared persistence layer
• SMTP relay delivers messages to external domains

---

Use Cases

• Self-hosted mail servers
• Local development mail infrastructure
• Integration tests (email-heavy systems)
• Custom email gateways
• Embedded mail services in Dart backends

---

Requirements

• Dart 3.9+
• TLS certificates (self-signed supported)
• Open network ports for SMTP / IMAP

---

Issues & Feature Requests

Please report issues and request features via the issue tracker.

---

Author

Graciliano M. Passos: gmpassos@GitHub.

---

License

Dart free & open-source license.