Plunk
What it is
Plunk is an open-source email platform for transactional messages, marketing campaigns, and automated workflows built around one contact list. Its API and SMTP relay can deliver receipts, password resets, and other event-triggered email. Workflows begin with product events and can add delays, conditions, branches, email actions, and outbound webhooks. Campaigns can address an entire list or a segment, with tracking for opens, clicks, bounces, and unsubscribes. For inbound mail, one MX record sends parsed message content to an endpoint as JSON, and inbound messages can start workflows. Plunk provides a REST API, Node.js and Python SDKs, SMTP, webhooks, email templates, delivery event webhooks, and an MCP server for MCP clients such as Claude Code, Claude Desktop, and Cursor. The AGPL-3.0 platform runs on customer infrastructure through Docker Compose or as a hosted service. Hosted data is primarily stored in the EU/EEA, while delivery may pass through non-EU regions. Rendered email bodies are deleted after 90 days; statistics and activity remain.
For and against
For
- API and SMTP support transactional email
- Workflows include branching and outbound webhooks
- Campaign analytics track opens and unsubscribes
- Inbound email can trigger workflows
- Free plan includes 1,000 emails monthly
Against
- Rendered email bodies are deleted after 90 days
- Email delivery may transit non-EU regions
- Hosted DPA does not cover self-hosted deployments
The verdict
Plunk combines transactional delivery, campaigns, workflows, and inbound processing around one contact list. Its free and usage-based plans, APIs, and self-hosting option give teams several deployment paths.
Who it suits
Plunk suits developers, marketers, and teams sharing email templates. It also fits organizations wanting hosted or Docker-based self-hosting options.
Plans and prices
Free
1,000 emails per month
Read 23 Sep 2026 · useplunk.com
Free forever
1,000 emails / mo · unlimited contacts · Plunk branding on emails
Read 8 Oct 2026 · useplunk.com
Pay as you grow
Unlimited emails · unlimited contacts · no Plunk branding · monthly spend cap
Read 8 Oct 2026 · useplunk.com
On the record
- Campaigns and analytics
- Campaigns can target a full list or segment, with tracking for opens, clicks, bounces, and unsubscribes.useplunk.com · read 8 Oct 2026
- Compliance scope
- The DPA applies to Plunk's hosted service and says self-hosted deployments are not covered by it.useplunk.com · read 8 Oct 2026
- Data residency
- The DPA states that primary data storage is in the EU/EEA on Hetzner infrastructure, while email delivery may transit non-EU regions through AWS SES.useplunk.com · read 8 Oct 2026
- Data security
- The DPA describes HTTPS-only API access using TLS 1.2+, encrypted database connections, limited-expiry authentication tokens, rate limiting, and project-level data isolation.useplunk.com · read 8 Oct 2026
- Inbound email
- One MX record enables inbound email at the domain, with parsed message content delivered to an endpoint as JSON and inbound messages able to trigger workflows.useplunk.com · read 8 Oct 2026
- Integrations
- Plunk offers a REST API, SDKs including Node.js and Python, SMTP support, webhooks, and an MCP server that works with MCP clients such as Claude Code, Claude Desktop, and Cursor.useplunk.com · read 8 Oct 2026
- Notable limit
- Rendered email bodies are deleted after 90 days, while stats and activity are kept.useplunk.com · read 8 Oct 2026
- Product
- Plunk is an open-source email platform for transactional email, marketing campaigns, and automated workflows against one contact list.useplunk.com · read 8 Oct 2026
- Self-hosting
- The AGPL-3.0 licensed platform can be deployed on the customer's infrastructure using Docker Compose.useplunk.com · read 8 Oct 2026
- Support
- The maker invites customer feedback and lists a Discord community on its site.useplunk.com · read 8 Oct 2026
- Transactional email
- It supports API and SMTP delivery for receipts, password resets, and other event-driven email.useplunk.com · read 8 Oct 2026
- Who it is for
- The maker describes Plunk as an independent SaaS run by a person, and its editor page describes use by developers, marketers, and teams sharing templates.useplunk.com · read 8 Oct 2026
- Workflows
- Workflows start from product events and can include delays, conditions, branches, email steps, and outbound webhooks.useplunk.com · read 8 Oct 2026
