3 open source alternatives to SendGrid
Transactional email API for apps, now Twilio SendGrid. Here are the open source projects real teams use instead — ranked by fit, with honest pros and cons for each.
What people don't love about SendGrid
- Pricing escalates sharply once you outgrow the starter tier.
- Shared-IP deliverability issues when neighbours spam.
- Support response times complaints on mid-tier plans.
Current SendGrid pricing (for reference): Free 100/day; paid from $19.95/month for 50k emails.
Quick comparison
| Alternative | Best for | License | Self-host | Hosted cloud? |
|---|---|---|---|---|
|
Postal Self-hosted mail server for sending transactional and bulk email. |
Running a full transactional mail server with a web UI and per-server tracking. | MIT | ★★★★☆ | Self-host only |
|
Listmonk Self-hosted newsletter and mailing list manager. |
Newsletters and bulk sends where SendGrid's per-email pricing hurts. | AGPL-3.0 | ★★☆☆☆ | Self-host only |
|
Mautic Open source marketing automation platform. |
Marketing sequences and drip campaigns on your own infrastructure. | GPL-3.0 | ★★★★☆ | Yes |
1. Postal — Running a full transactional mail server with a web UI and per-server tracking.
Self-hosted mail server for sending transactional and bulk email.
Strengths
- Web UI, SMTP and HTTP API out of the box.
- Per-server tracking (opens, clicks, bounces).
- Modular MariaDB + RabbitMQ architecture.
Weaknesses
- Running a real mail server is a deliverability project, not an install.
- IP warm-up and SPF/DKIM/DMARC on you.
- Many cloud providers block outbound :25 entirely.
2. Listmonk — Newsletters and bulk sends where SendGrid's per-email pricing hurts.
Self-hosted newsletter and mailing list manager.
Strengths
- Fast Go binary — single executable.
- Clean UI and import/export tools.
- Bring-your-own-SMTP (Amazon SES, Postmark, etc.).
Weaknesses
- No drag-and-drop visual builder.
- Deliverability depends on your SMTP setup.
- Not a visual marketing suite — plain newsletter focus.
Listmonk homepage · Source on GitHub · SendGrid vs Listmonk →
3. Mautic — Marketing sequences and drip campaigns on your own infrastructure.
Open source marketing automation platform.
Strengths
- Full marketing automation — campaigns, landing pages, scoring.
- Large ecosystem.
- Strong for B2B lead nurturing.
Weaknesses
- Heavy self-host setup (PHP + queue + cron).
- UI is complex and has a learning curve.
- Smaller company behind — not as polished as Mailchimp.
Not what you're looking for?
Browse other tools in Transactional Email, or check out open source projects by category on the full category index.
Other SaaS in Transactional Email
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