Posta
Posta is a self-hosted email delivery platform for sending and receiving email through an HTTP API.
What Posta is
Posta is a self-hosted email delivery platform for sending and receiving email through an HTTP API. It supports API sending, SMTP relay, inbound mail, and website form submissions. Its REST API handles transactional, batch, and templated messages, with attachments, scheduled delivery, retries, and priority queues. Incoming mail can arrive through built-in SMTP with TLS or an authenticated webhook; forwarding and real-time SSE notifications are also supported. Templates include versioning, localization, visual editing, and previews, while campaigns add A/B testing and send-rate throttling. Posta works with multiple SMTP providers and supports domain verification with SPF, DKIM, and DMARC. It offers event webhooks with filtering, HMAC signing, retries, and delivery tracking. The maker lists SDKs for Go, PHP, Java, and .NET, plus Prometheus and OAuth/SSO integrations. Posta is free and open source under AGPL-3.0, and runs on customer infrastructure, with a Docker Compose startup option. Web form messages are disabled by default and have documented submission limits.
Good
- Supports API sending, SMTP relay, inbound mail, and forms
- Includes scheduled, batch, and templated email sends
- Offers template versioning, localization, and visual editing
- Provides delivery webhooks with HMAC signing and retries
- Free, open source, and self-hosted
Watch out
- Web form messages are disabled by default
- Forms have documented hourly and daily submission limits
- Requires deployment on customer infrastructure
Who it suits
Posta suits teams that want to operate email delivery on their own infrastructure and need both outbound and inbound email. It may also suit developers looking for an HTTP API, SMTP relay, templates, and event webhooks.
Verdict
Posta combines outbound email, inbound handling, templates, campaigns, and webhooks in a self-hosted package. Its main consideration is operating it on your own infrastructure, with form submissions disabled by default and subject to limits.
Plans and prices
From Posta's own pricing page, checked 8 Oct 2026.
| Plan | Price | What it gives you |
|---|---|---|
| Self-hosted, AGPL-3.0 | Free | Free and open source · runs on your own infrastructure; no published usage limits |
The facts
Each one read from Posta's own pages, with the date it was checked.
What it does
- Data controls
- Posta describes isolated workspaces and provides data export, import, and GDPR deletion tools.checked 8 Oct 2026
- Delivery methods
- bothchecked 20 Sep 2026
- Deployment
- Posta is self-hosted on the customer’s infrastructure and the maker provides a Docker Compose startup option.checked 8 Oct 2026
- Email delivery
- The REST API supports transactional, batch, and templated sends, attachments, scheduled sending, retries, and priority queues.checked 8 Oct 2026
- Event webhooks
- Yeschecked 20 Sep 2026
- Form messages limit
- Web form messages are disabled by default; the documented default limits include 200 submissions per form per hour and 1,000 per workspace per day.checked 8 Oct 2026
- Inbound email
- Posta can receive inbound mail through built-in SMTP with TLS or an authenticated webhook, and supports forwarding and real-time SSE notifications.checked 8 Oct 2026
- Integrations
- The maker lists official SDKs for Go, PHP, Java, and .NET, plus Prometheus integration and OAuth/SSO providers including Google, Keycloak, and authentik.checked 8 Oct 2026
- License
- The maker identifies Posta as free and open source under AGPL-3.0.checked 8 Oct 2026
- Security
- Listed security features include hashed API keys, optional key expiration and IP allowlists, JWT authentication, role-based access, two-factor authentication, rate limiting, and session management.checked 8 Oct 2026
- SMTP and domain setup
- Posta supports multiple SMTP providers and domain verification with SPF, DKIM, and DMARC.checked 8 Oct 2026
- Template options
- bothchecked 20 Sep 2026
- Templates and campaigns
- Templates support versioning, localization, visual editing, and preview; campaigns support scheduled delivery, A/B testing, and send-rate throttling.checked 8 Oct 2026
- Ways to use it
- It supports API sending, SMTP relay, inbound email, and website form submissions.checked 8 Oct 2026
- Webhooks
- Webhooks support event filters, HMAC signing, retries, and delivery tracking.checked 8 Oct 2026
- What it does
- Posta is a self-hosted email delivery platform for sending and receiving email through an HTTP API.checked 8 Oct 2026
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