12 Best Open Source Postmark Alternatives
A curated collection of the 12 best open source and self-hosted alternatives to Postmark in 2026.
Looking for a free, privacy-friendly, or self-hosted replacement for Postmark in 2026? The top open-source alternative is Plunk — Open-source transactional email platform.
Other highly rated open-source Postmark alternatives include useSend, Sendune and Sessy.
Open-source transactional email platform
Plunk is an open-source, self-hostable email platform designed for transactional emails, marketing campaigns, and automated workflows. Built with privacy in mind, it offers transparent pricing, no contact limits, and full control over your email infrastructure. - Transactional & Marketing Emails: Send both transactional emails and marketing campaigns from a single platform. - Automated Workflows: Trigger workflows based on events sent from your code, with a visual canvas for full transparency. - Inbound Email Handling: Receive emails at your domain by adding an MX record, turning replies into contacts and triggering workflows. - Unlimited Contacts: Store unlimited contacts for free; pay only per email sent ($0.001 per email). - Self-Hosting & Open Source: Fully inspectable, forkable, and self-hostable under AGPL-3.0 license. - MCP Server Integration: Connect AI agents (Claude, Cursor) to manage emails via the Model Context Protocol. - Email Editor & SMTP: Visual editor for emails or direct HTML editing, plus SMTP support for existing clients. - Analytics & Segments: Track delivery, opens, clicks, and bounces per send, with dynamic segments that update in real-time. - License: AGPL-3.0 - Hosting: EU-based cloud or self-hosted via Docker Compose - GitHub Stars: 5,000+ - Setup Time: Under 5 minutes for domain configuration and first send - Exit Strategy: Full control via Docker Compose for seamless migration away from the cloud service.
Open source email platform for everyone
Send product, transactional and marketing emails. Pay only for what you send and not for storing contacts. - Pay-per-use pricing: Only pay for emails sent, not for storing contacts - Multi-purpose email sending: Supports product, transactional, and marketing emails - Real-time analytics: Track deliveries, opens, clicks, bounces and unsubscribes with searchable logs - Visual email editor: Notion-like WYSIWYG editor for designing campaigns without code - Contact management: Import/export contacts, manage lists, and track subscription status - Suppression list: Automatically blocks bounced and complained emails - SMTP relay: Drop-in SMTP service that works with any application or framework - Multi-language SDKs: TypeScript, Python, Go, and PHP libraries available - Self-hosting: Deploy in minutes with open source code - Free tier: Send up to 3000 emails/month with 100/day limit - Open source: Full source code available on GitHub - Self-hosting: Deployable in minutes with Docker or direct installation - API-first: RESTful API with SDKs for multiple programming languages - Database: Uses PostgreSQL for reliable data storage - Infrastructure: Requires Node.js runtime and Redis for caching - Hosting: Can be deployed on any cloud provider or on-premise servers
No-code dashboard for AWS SES email management
Sendune simplifies AWS SES by providing a no-code dashboard to manage all your transactional and marketing emails. Connect your AWS account and handle everything from contact management to email delivery with ease. - No-Code Dashboard: Manage AWS SES without technical complexity. - Contact Management: Organize contacts with tag-based systems. - Drag-and-Drop Email Designer: Create and customize emails visually. - Template Management: Store and reuse email templates. - Automations: Set up workflows for email sequences and triggers. - Reputation Management: Monitor SPF, DMARC, and DKIM compliance. - Analytics: Track email performance and deliverability. - 99.95% Uptime SLA: Reliable service with high availability. Sendune is a fully hosted service, but the underlying email designer is open-source and available on GitHub. The platform integrates seamlessly with AWS SES, requiring no additional infrastructure setup.
Open-source email observability for AWS SES
Sessy is an open-source email observability tool for AWS SES. Track deliveries, bounces, opens, clicks, and complaints in a dashboard you own. Self-host it or use the hosted version. - Real-time event tracking: Capture every SES event (sends, deliveries, bounces, complaints, opens, clicks) as it happens - Bounce & reputation monitoring: Track bounce rates by type and spot complaint spikes to protect sender reputation - Engagement analytics: Open and click tracking with unique counts and 30-day trend charts - Multi-source management: Separate email streams by application or environment with dedicated webhook URLs - MCP server integration: Query email data directly from AI agents like Claude Code or Cursor - Flexible deployment: Self-host with Docker or PostgreSQL, or use the hosted beta version - Cost-effective: Free self-hosted version with no per-email pricing - Deployment: Docker or Kamal on your own infrastructure - Database: SQLite by default, PostgreSQL support available - Setup: No AWS credentials or complex integrations required - Data ownership: Your data stays on your server with no limits on volume or retention - Migration: Switch between self-hosted and hosted versions seamlessly
Open-source email API for developers
Hyvor Relay is an open-source email API designed for developers who need reliable, scalable, and self-hostable email delivery. Whether you're sending transactional emails, newsletters, or automated notifications, Relay provides a clean REST API with built-in deliverability best practices. - Email API: Send emails via a simple, idempotent REST API supporting HTML/plain text, attachments, custom headers, and multiple recipients. - Automated Workflows: Manage domains, API keys, suppressions, and webhooks programmatically with a powerful scope-based API. - Real-time Webhooks: Receive instant notifications for deliveries, bounces, complaints, and domain verifications. - Domain & DKIM Management: Enforce DKIM signing and manage multiple domains for maximum deliverability and trust. - Project Isolation: Organize work into isolated projects, each with dedicated domains, keys, and webhooks under a single account. - Bounce & Complaint Handling: Automatically manage bounces, complaints, and suppressions to maintain sender reputation. - Email Logs: Access detailed delivery logs with headers, status, and SMTP traces (30-day retention). - Built-in DNS Server: Automate DNS configuration (MX, SPF, DKIM) with an integrated DNS server—no manual setup required. - Observability: Native integrations with Prometheus and Grafana for monitoring performance, alerts, and logs. - Scalability: Horizontal scaling with Docker Swarm on any cloud or on-premises infrastructure. - Health Checks: Instant alerts for server issues, DNS errors, or IP reputation drops to proactively address problems. Hyvor Relay is fully open-source under the AGPL-3.0 license, allowing you to deploy, inspect, and modify the software on your own infrastructure with zero vendor lock-in. The self-hosted version includes all features, with the only differences being licensing terms and support options. For enterprises requiring commercial licensing without AGPL obligations, an Enterprise License is available, offering priority updates, expert support, and SLAs starting at €10,000/year. - SPF, reverse DNS, multiple IPs, and queue isolation baked in. - Automatic suppression lists and feedback loop management. - Extensive documentation on SMTP and email deliverability best practices. - Deployable on any cloud or on-premises setup using Docker Swarm. - Requires SSO (Single Sign-On) for authentication. For more details, visit the official documentation.
00 is an open-source email API and infrastructure solution that allows developers to own and control their email stack.
00 is an open-source email API and infrastructure solution that allows developers to own and control their email stack.
Self-hosted email platform for Amazon SES
Wraps is an open-source email infrastructure platform designed to simplify Amazon SES deployment and management. It provisions SES, DynamoDB, Lambda, and other AWS services into your account with a single command, enabling you to send emails while maintaining full control over your data and costs. - One-Command Deployment: Instantly deploy SES, DynamoDB, Lambda, and IAM roles with wraps email init. - Type-Safe SDK: Send emails with full TypeScript type inference using the @wraps.dev/email SDK. - Templates-as-Code: Store and version email templates directly in your repository. - Real-Time Analytics: Track every email send with live analytics powered by your own DynamoDB tables. - Reputation Protection: Automatic bounce and complaint handling with suppression to prevent re-sends. - Zero Stored Credentials: Access via OIDC-federated IAM roles—your AWS keys never leave your account. - Workflows & Automation: Build and automate email workflows with visual editors and TypeScript. - Cost Efficiency: Pay AWS directly at $0.10 per 1,000 emails, significantly lower than competitors. Wraps operates on a Bring Your Own Cloud (BYOC) model, where the control plane (dashboard, templates, workflows) is hosted by Wraps, while the data plane (SES, DynamoDB, Lambda) runs entirely in your AWS account. This ensures: - Full Data Ownership: Your email delivery data remains in your AWS account. - AWS Cost Transparency: You pay AWS directly for sending costs. - Open Source Core: The platform is open-source under AGPL-3.0, with the option to use Wraps-hosted services for convenience.
Email inbox API for AI agents to create, send, and receive messages via REST
AgentMail provides AI agents with real email inboxes, enabling them to create, send, receive, and search messages entirely via REST API. Built specifically for autonomous agents and agentic workflows, it eliminates the need for manual email handling. - Inboxes API: Create, manage, and operate email inboxes entirely via API with custom domains and multi-tenancy support - Threads & Replies: Full email thread management including attachments and realtime events - Semantic Search: Advanced search capabilities to find relevant emails quickly - Data Extraction: Automatically extract structured data from emails - SDKs & MCP: Python, TypeScript, and CLI SDKs with Model Context Protocol (MCP) support - Agent Integrations: Native support for popular AI agents like Claude Code, Hermes, OpenClaw, Codex, Cursor, and Grok - Security: Agent Armor feature to screen inbound mail before agents process it - Scalability: Built for enterprise-grade performance with global infrastructure AgentMail is a fully managed cloud service with no self-hosting option available. The platform provides REST APIs, SDKs (Python, TypeScript, CLI), and MCP servers for seamless integration with AI agent frameworks. All infrastructure is managed by AgentMail with enterprise-grade security and compliance standards.
Open-source customer engagement platform
Dittofeed is an open-source, embeddable customer engagement platform designed for automating messaging across multiple channels including email, SMS, mobile push notifications, and WhatsApp. Built with flexibility in mind, it offers a low-code customer segmentation engine, customizable message templates, and an intuitive drag-and-drop journey builder for creating automated messaging workflows. - Omni-channel Messaging: Support for email, SMS, push notifications, and WhatsApp - Embedded Components: Add messaging features directly within your SaaS application via iframe or React component - Journey Builder: Visual drag-and-drop interface for creating automated messaging workflows - Customer Segmentation: Low-code UI for powerful segmentation with customizable conditions - Template Editor: Easy-to-use editor for creating personalized message templates with subscription controls - Self-hosting: Full control over data with self-hosting capabilities - HIPAA Compliance: Built-in support for healthtech companies requiring HIPAA compliance - Developer-Friendly: Comprehensive documentation, community support via Discord, and changelog updates Dittofeed is designed for self-hosting, giving organizations full control over their data and infrastructure. The platform is built with modern web technologies and can be deployed on any cloud provider or on-premise infrastructure. The GitHub repository provides complete source code, deployment instructions, and ongoing updates. The project is actively maintained with regular releases and community-driven development.
Email platform for developers and marketers
The best way to reach humans instead of spam folders. Deliver transactional and marketing emails at scale with Resend’s developer-first platform. - Developer-Friendly APIs & SDKs: Integrate seamlessly with Node.js, Python, Ruby, PHP, Go, Rust, Java, Elixir, .NET, REST, and SMTP. Supports frameworks like Next.js, Remix, Nuxt, Express, Hono, Redwood, Bun, and Astro. - React Email Integration: Build beautiful email templates using React components with react-email, eliminating complex HTML table layouts. - Test Mode: Simulate email events and API interactions without accidentally sending real emails to real people. - Modular Webhooks: Receive real-time notifications for email delivery, opens, bounces, clicks, and spam complaints directly to your server. - Audience Management: Group and control contacts with intuitive tools, import lists of any size, and gain full visibility into contact attributes. - Broadcast Analytics: Track audience interactions with detailed insights to optimize email campaigns. - Proactive Blocklist Tracking: Monitor DNS blocklists (e.g., Spamhaus) and generate removal requests automatically. - Global Infrastructure: Reduce latency by sending emails from regions closest to your users, including North America, South America, Europe, and Asia. - BIMI & VMC Support: Showcase your logo and company branding with Brand Indicators for Message Identification (BIMI) and Verified Mark Certificates (VMC). - Managed Dedicated IPs: Get fully managed dedicated IPs with automatic warming and scaling based on your sending volume. - Dynamic Suppression List: Comply with email regulations like CAN-SPAM by preventing repeated sends to uninterested recipients. - IP & Domain Monitoring: Track DNS configurations for errors or regressions and receive alerts for deliverability issues. - DNS Record Verification: Secure your email communication with DKIM, SPF, and DMARC to protect your sender reputation. - Battle-Tested Infrastructure: Rely on a platform with reputable IPs used by trustworthy senders and distributed workloads across multiple IP pools. Resend is a cloud-based email service and does not offer self-hosting options. It is designed for developers and businesses seeking a scalable, managed email solution with minimal setup and maintenance overhead. - Pricing: Free tier available; paid plans for higher volumes and advanced features. - Privacy & Compliance: GDPR compliant with EU data residency options. No AI dependency (noAi: false).
Reliable email sending API & SMTP service
MailerSend is a cloud-based email sending service designed for developers and businesses. It provides a robust API and SMTP relay for sending transactional and bulk emails reliably. - Email API & SMTP: Send emails via API or SMTP with high deliverability - Dynamic Templates: Create and manage responsive email templates - Inbound Routing: Process incoming emails with custom routing rules - Email Verification: Clean and validate email lists before sending - User Management: Multi-user access with role-based permissions - Domain Management: Support for multiple domains and DMARC monitoring - SMS Integration: Send transactional SMS in the US and Canada - Split Testing: Optimize email campaigns with A/B testing - Webhooks: Real-time notifications for email events - MCP Server: New feature for enhanced integration capabilities MailerSend is a fully managed cloud service with no self-hosting option. The official Node.js SDK is available for integration at https://github.com/mailersend/mailersend-nodejs.
Customer engagement infrastructure platform
Knock is customer engagement infrastructure designed to activate your data and ship cross-channel messaging without limits. Purpose-built for control, speed, and collaboration, it unifies product, marketing, and transactional messaging into a single platform. - Cross-channel messaging: Send messages across email, SMS, push, chat, and in-app channels - AI-native workflows: Build complex messaging journeys with single prompts and generate client-safe emails - Unified data activation: Ingest real-time data from products, tools, and warehouses to trigger relevant messaging - User-first controls: Implement preference centers and send windows to respect user time - In-app messaging: Ship paywalls, dialogs, and nudges powered by your own components - Collaboration tools: Enable non-engineers to edit copy and targeting with Knock's intuitive interface - Developer tools: Access MCP server and CLI for streamlined account management - AI-powered email generation: Create beautiful, branded emails without manual coding Knock is a fully managed SaaS platform with no self-hosting option. The service provides comprehensive APIs, SDKs, and developer tools including a Node.js client library for seamless integration. All infrastructure is managed by Knock with enterprise-grade security and compliance standards.
About Postmark
Postmark is a fast and reliable email delivery service designed for developers. It ensures transactional and marketing emails reach the inbox quickly and consistently.
Key Features of Postmark
- Email API for programmatic email sending
- SMTP Service for traditional email delivery
- Message Streams to organize and track email flows
- Transactional Email for critical notifications
- Email Templates for consistent branding
- Inbound Email to receive and process incoming messages
- Analytics & Retention for tracking performance and compliance
- Bulk API for sending large volumes of emails
- Integrations with popular development tools and platforms
Tech / Self-Hosting
Postmark is a fully managed cloud service and does not support self-hosting. It is designed for ease of use with robust APIs and SDKs for seamless integration into applications.