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Posta

goposta.dev

Free plan WebAPISelf-hosted
Visit goposta.dev
Spec score 7.9 #25 of 41 in Transactional Email Software

What it is

Posta is a free, AGPL-3.0 self-hosted platform for sending and receiving email through an HTTP API. It supports API sending, SMTP relay, inbound mail, and website form submissions. The REST API handles transactional, batch, and templated messages with attachments, scheduling, retries, and priority queues. Incoming mail can arrive through built-in SMTP with TLS or an authenticated webhook, with forwarding and real-time SSE notifications. Templates offer versioning, localization, visual editing, and preview; campaigns add scheduling, A/B testing, and send-rate throttling. Posta supports multiple SMTP providers, SPF, DKIM, and DMARC verification, plus SDKs for Go, PHP, Java, and .NET. Security controls include hashed API keys, optional expiration and IP allowlists, JWT authentication, roles, two-factor authentication, rate limiting, and session management. It runs on customer infrastructure, with Docker Compose startup, isolated workspaces, data import/export, and GDPR deletion tools.

Spec sheet

What it does
Posta is a self-hosted email delivery platform for sending and receiving email through an HTTP API.Read 8 Oct 2026 · goposta.dev
Deployment
Posta is self-hosted on the customer’s infrastructure and the maker provides a Docker Compose startup option.Read 8 Oct 2026 · goposta.dev
Integrations
The maker lists official SDKs for Go, PHP, Java, and .NET, plus Prometheus integration and OAuth/SSO providers including Google, Keycloak, and authentik.Read 8 Oct 2026 · goposta.dev
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.Read 8 Oct 2026 · goposta.dev
License
The maker identifies Posta as free and open source under AGPL-3.0.Read 8 Oct 2026 · goposta.dev
Data controls
Posta describes isolated workspaces and provides data export, import, and GDPR deletion tools.Read 8 Oct 2026 · goposta.dev
Delivery methods
bothRead 20 Sep 2026 · github.com
Email delivery
The REST API supports transactional, batch, and templated sends, attachments, scheduled sending, retries, and priority queues.Read 8 Oct 2026 · goposta.dev
Event webhooks
YesRead 20 Sep 2026 · github.com
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.Read 8 Oct 2026 · docs.goposta.dev
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.Read 8 Oct 2026 · goposta.dev
SMTP and domain setup
Posta supports multiple SMTP providers and domain verification with SPF, DKIM, and DMARC.Read 8 Oct 2026 · goposta.dev
Template options
bothRead 20 Sep 2026 · github.com
Templates and campaigns
Templates support versioning, localization, visual editing, and preview; campaigns support scheduled delivery, A/B testing, and send-rate throttling.Read 8 Oct 2026 · goposta.dev
Ways to use it
It supports API sending, SMTP relay, inbound email, and website form submissions.Read 8 Oct 2026 · goposta.dev
Webhooks
Webhooks support event filters, HMAC signing, retries, and delivery tracking.Read 8 Oct 2026 · goposta.dev

Plans and prices

Self-hosted, AGPL-3.0 Free Free and open source · runs on your own infrastructure; no published usage limits Read 8 Oct 2026 · goposta.dev

Every Posta plan and price →

Strong points and limits

Strong points

  • Free AGPL-3.0 self-hosted deployment
  • Supports API sending and SMTP relay
  • Inbound email with webhook options
  • Versioned and localized templates
  • Official SDKs for four languages

Limits

  • Web forms are disabled by default
  • Documented form submission limits apply
  • Requires customer-managed infrastructure
  • No published hosted pricing

Who it suits

Posta suits teams that want open-source email delivery on their own infrastructure. It fits developers needing API, SMTP, inbound mail, templates, webhooks, and deployment controls.

Verdict

Posta covers outbound, inbound, and workflow email in a self-hosted package with extensive controls. Teams should account for infrastructure ownership and the documented form defaults and limits.

Where Specifiction places it

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