Important: deliverability is on you
Self-hosted email needs SPF, DKIM, and DMARC set up correctly and a warmed IP or a relay like Amazon SES. Several tools here do not send mail themselves and rely on SES.
Alternatives / Mailgun
8 open-source alternatives
8 Best Open Source Mailgun Alternatives in 2026
Looking for an open source Mailgun alternative? We compared 8 open source email sending platforms by license, Amazon SES support, self-hosting, and maintenance. Several only manage SES sending for you, so deliverability still depends on how you configure DNS and your sending reputation.
Written by Maxime DERAME
Last updated:
Best Mailgun alternatives at a glance
| Alternative | Best for | License |
|---|---|---|
| Billion Mail | Self-hosted SMTP and email marketing | AGPL-3.0 |
| Plunk | Marketing and transactional email on SES | AGPL-3.0 |
| useSend | Email API on SES with SMTP relay | AGPL-3.0 |
| Sendune | SES management (only designer is open) | MIT for public email-designer repository |
| Sessy | SES event dashboard, does not send | O'Saasy License |
| Hyvor Relay | Self-hosted email API with DNS automation | AGPL-3.0 / commercial Enterprise |
| DoubleZero | Email API deployed to your cloud (stalled) | AGPL-3.0 |
| Wraps | React email templates on your SES | AGPL-3.0 + enterprise license |
How we chose these Mailgun alternatives
We looked for open-source tools that send transactional and marketing email through an API like Mailgun. We verified each project's license, recent activity, stars, and self-hosting in its repository, and flag projects that are only partly open or stalled. See our methodology for the full criteria.
Closest to Mailgun
Hyvor Relay is a self-hosted email API with built-in DNS automation and webhooks, and Plunk combines marketing and transactional email in one platform. useSend is an open-source email platform on Amazon SES with an SMTP relay and typed SDKs.
SES-based tools
Wraps builds templates as React components and deploys to your AWS account with SES. Sendune manages transactional and marketing email through SES, but only its public email designer repository is open. Sessy is a dashboard that tracks SES events and does not send email. DoubleZero deploys an email API to your cloud, with its last commit in October 2024.
Self-hosted mail server
Billion Mail is a self-hosted email marketing platform with its own SMTP server and AI email creation, and you must configure sending authentication correctly.
Important: licenses
Sessy uses the O'Saasy License, Hyvor Relay is AGPL-3.0 with a commercial Enterprise tier, and Sendune is only partly open source. Plunk, useSend, DoubleZero, Billion Mail, and Wraps are AGPL-3.0.
Maintenance status
Most had commits within days of this update. DoubleZero looks stalled.
Why look for a Mailgun alternative?
Mailgun is a proprietary email API priced by volume, with logs and recipient data stored on its infrastructure. Open-source platforms avoid per-email platform fees and keep data in your account, but you manage sending reputation, SPF, DKIM, and DMARC yourself, and most still depend on Amazon SES.
billionmail.com
AGPL-3.0 self-hosted email platform combining SMTP infrastructure with newsletters, marketing campaigns, analytics, domain configuration, and campaign management. It uses components such as Postfix, Dovecot, and Rspamd, so it operates more of the delivery stack than a provider-backed email API.
15.9K1.8KAGPL-3.0Self-hosted
Pricing: Open-source self-hosted platform.
- Includes SMTP infrastructure and campaign tooling
- Newsletters, analytics, and domain management
- SPF, DKIM, and DMARC guidance with no built-in sending limit
- More infrastructure to operate than Resend
- Deliverability and sender reputation are your responsibility
- Recent commit cadence is slower than some newer projects
useplunk.com
AGPL-3.0 email platform combining transactional API delivery, SMTP relay, campaigns, automations, contacts, segments, inbound email, analytics, custom domains, and SPF/DKIM setup. Can be self-hosted or used through a managed service.
5.5K418AGPL-3.0Self-hosted
Pricing: Self-hosted open-source platform with hosted service available.
- Transactional API and SMTP relay
- Campaigns, contacts, automations, and segmentation
- Inbound email, analytics, custom domains, and self-hosting
- Smaller ecosystem than Resend
- Marketing features may be unnecessary for transactional-only teams
- Self-hosting still requires a delivery provider or operating infrastructure
usesend.com
AGPL-3.0 self-hosted email platform built around Amazon SES, with transactional API, SMTP relay, marketing campaigns, contacts, visual editor, delivery logs, open/click tracking, bounce tracking, suppressions, analytics, and TypeScript, Python, Go, and PHP SDKs.
4.7K440AGPL-3.0Self-hosted
Pricing: Self-hosted open-source layer; Amazon SES usage and AWS infrastructure are billed separately.
- Amazon SES backend with transactional API and SMTP relay
- Campaigns, contacts, logs, analytics, bounces, and suppressions
- Multiple SDKs and self-hosting
- Depends on Amazon SES and AWS configuration
- Not an independent delivery network
- Smaller ecosystem than Resend
sendune.com
Platform described around Amazon SES and AWS SNS for email, SMS, contacts, OTPs, campaigns, and automation. The public repository associated with the product is an MIT-licensed drag-and-drop email designer, not the complete Sendune application; do not treat the entire platform as open source based on that repository.
2.3K144MIT for public email-designer repositoryFull product source not verified
Pricing: Product terms and source availability vary; verify the full platform before adoption.
- AWS SES integration and transactional email positioning
- Marketing email, contacts, SMS via SNS, and OTP workflows
- Public MIT email-template designer
- Public repository does not contain the full platform
- Open-source status of the complete product is unclear
- Depends on AWS and repository stars refer to the editor
github.com
AGPL-3.0 transactional email API, also known as 00, with HTML and Markdown email, attachments, provider options, and AWS SES integration. The repository has seen little or no recent development, making it a riskier choice for a new production stack.
1.2K66AGPL-3.0Self-hosted
Pricing: Open-source self-hosted project; assess maintenance before production use.
- Developer-focused transactional API
- HTML and Markdown email with attachments
- AWS SES and self-hosting
- Little or no recent repository development
- Limited modern dashboard functionality
- Higher maintenance and production risk
sessy.dev
Self-hosted SES event dashboard that captures delivery, bounce, complaint, open, click, reject, and delay events and exposes searchable logs and analytics. It does not send email or replace SES. Current versions use the O'Saasy License, a source-available rather than OSI-approved open-source license.
94145O'Saasy LicenseSelf-hosted
Pricing: Source-available self-hosted software; review current license terms.
- Searchable SES events for deliveries, bounces, complaints, opens, and clicks
- Reputation monitoring, multiple projects, and analytics
- SQLite or PostgreSQL, Docker, and MCP server
- Not an email sending API
- Requires Amazon SES
- Source-available license and no campaign/template replacement
relay.hyvor.com
AGPL-3.0 email API and SMTP infrastructure with DKIM and SPF management, bounce processing, suppression handling, webhooks, logs, project isolation, monitoring, Prometheus/Grafana, Docker, and horizontal scaling. Commercial Enterprise licensing is also available.
91965AGPL-3.0 / commercial EnterpriseSelf-hosted
Pricing: AGPL-3.0 self-hosting with a separate Enterprise license available.
- REST email API and own SMTP infrastructure
- DKIM, SPF, bounces, suppressions, and webhooks
- Logs, multi-tenancy, Prometheus/Grafana, Docker, and scaling
- More infrastructure responsibility than Resend
- You own deliverability and reputation
- Smaller ecosystem and Enterprise license may be needed
wraps.dev
Wraps is a developer-friendly email platform where templates are React components and automations are written in TypeScript, deployed to your own AWS account with SES. The code is AGPL-3.0 with enterprise features under a commercial license, and AWS charges about $0.10 per 1,000 emails. It is a very young project.
648AGPL-3.0 + enterprise licenseSelf-hosted
Pricing: Free to start; AWS usage is billed to your account, and enterprise features are paid.
- Email as React components and TypeScript automations
- Runs in your own AWS account
- AGPL-3.0 core
- Requires an AWS account
- Very young project with about 63 stars
Compare Mailgun alternatives
| Alternative | Type | License | Self-hosted | Best for |
|---|---|---|---|---|
| Billion Mail | Email server | AGPL-3.0 | Yes | Own mail server |
| Plunk | Email platform | AGPL-3.0 | Yes | Closest replacement |
| useSend | Email API | AGPL-3.0 | Yes | Transactional email |
| Sendune | Email platform | MIT for designer repo | Partly | Teams already on AWS |
| Sessy | Event tracker | O'Saasy License | Yes | Tracking bounces and opens |
| Hyvor Relay | Email API | AGPL-3.0 + Enterprise | Yes | Replacing SES or Mailgun |
| DoubleZero | Email API | AGPL-3.0 | Your cloud | Check maintenance first |
| Wraps | Email platform | AGPL-3.0 | AWS account | TypeScript teams |
Which one should you choose?
Want the closest hosted-style email API you can self-host
Hyvor Relay is AGPL-3.0 with DNS automation and real-time webhooks.
Want marketing and transactional in one
Plunk covers marketing, transactional, and broadcast email.
Want an SMTP relay on SES
useSend charges nothing on self-hosting and uses Amazon SES for sending.
Want to run your own mail server
Billion Mail includes an SMTP server, but deliverability depends on your DNS setup.