# Outstamp

> Outstamp is a server-side transactional email API. Every project sends from its own isolated tenant, and Outstamp runs domains, events, webhooks and reputation for it.

- Send: POST https://api.outstamp.dev/v1/emails with Authorization: Bearer os_test_… or os_live_…. The answer is 202 with an email id, given only once the email is durably stored.
- Test keys never deliver to the internet. Recipients at @simulator.outstamp.dev produce deterministic events and webhooks.
- Webhooks are signed with HMAC-SHA256 (Outstamp-Signature: v1=), retried 10 times over 48 hours and replayable for 30 days.
- Mail is sent from the European Union.
- Emails are counted per recipient. Prices are in EUR, excluding VAT.
- Not available yet: SMTP relay, stored templates, official SDKs. The API is plain REST with an OpenAPI schema.
- Plans: Starter EUR 9/month for 10,000 emails, extra EUR 1.00 per 1,000; Growth EUR 25/month for 50,000 emails, extra EUR 0.80 per 1,000; Pro EUR 39/month for 100,000 emails, extra EUR 0.70 per 1,000; Scale EUR 179/month for 500,000 emails, extra EUR 0.45 per 1,000.

## Docs

- [Introduction](https://outstamp.scaling.pt/docs/)
- [Quickstart](https://outstamp.scaling.pt/docs/quickstart)
- [Test and Live](https://outstamp.scaling.pt/docs/environments)
- [Send API](https://outstamp.scaling.pt/docs/send-api)
- [Statuses and events](https://outstamp.scaling.pt/docs/statuses-events)
- [Webhooks](https://outstamp.scaling.pt/docs/webhooks)
- [Domains](https://outstamp.scaling.pt/docs/domains)
- [Suppressions and bounces](https://outstamp.scaling.pt/docs/suppressions)
- [Limits and errors](https://outstamp.scaling.pt/docs/limits-and-errors)
- [Retention and privacy](https://outstamp.scaling.pt/docs/retention-and-privacy)
- [Deliverability](https://outstamp.scaling.pt/docs/deliverability)
- [Migration](https://outstamp.scaling.pt/docs/migration)
- [Changelog and API policy](https://outstamp.scaling.pt/docs/changelog)
- [OpenAPI schema](https://outstamp.scaling.pt/openapi.json): the canonical machine-readable API schema

## Product

- [Product: the transactional email API](https://outstamp.scaling.pt/en/product): Sending, domains, events, signed webhooks, test mode and safety rails for transactional email, operated for you.
- [Pricing: transactional email from €9/month](https://outstamp.scaling.pt/en/pricing): Monthly plans in euros, excluding VAT, from €9 for 10,000 emails. Pay only for emails above your plan. Free to test, 30-day refund.
- [FAQ: transactional email with Outstamp](https://outstamp.scaling.pt/en/faq): Answers about getting started, deliverability, pricing, data retention and moving to Outstamp from another email provider.
- [Contact the founder of Outstamp](https://outstamp.scaling.pt/en/contact): Outstamp is run by its founder. Message @daminufe on X about moving from another provider, volumes above 1 million a month or the founder offer.

## Comparisons

- [A Resend alternative priced in euros](https://outstamp.scaling.pt/en/resend-alternative): Outstamp compared with Resend: an isolated tenant per project, prices in euros with invoices from Portugal, and public prices side by side.
- [A SendGrid alternative for transactional email](https://outstamp.scaling.pt/en/sendgrid-alternative): Outstamp compared with SendGrid: one transactional email API, an isolated tenant per project, signed webhooks and plans in euros from €9.
- [A Postmark alternative priced in euros](https://outstamp.scaling.pt/en/postmark-alternative): Outstamp compared with Postmark: transactional email with an isolated tenant per project, signed webhooks, a test simulator and prices in euros.
- [A Mailgun alternative for transactional email](https://outstamp.scaling.pt/en/mailgun-alternative): Outstamp compared with Mailgun: one transactional email API, an isolated tenant per project, signed webhooks and plans in euros from €9.

## Guides

- [Transactional email API for your app](https://outstamp.scaling.pt/en/transactional-email-api): Send password resets, receipts, sign-in links and alerts with one HTTP request. Safe retries, delivery events and signed webhooks. From €9/month.
- [Email API for developers: plain REST](https://outstamp.scaling.pt/en/email-api-for-developers): A plain REST email API for developers: curl, Node.js or Python, an OpenAPI schema, structured errors with request ids, test keys and docs for coding agents.
- [Email webhooks: signed, retried, replayable](https://outstamp.scaling.pt/en/email-webhooks): Outstamp sends email, domain and project events to your endpoint, signed with HMAC-SHA256, retried 10 times over 48 hours and replayable for 30 days.

## Optional

- [Full documentation](https://outstamp.scaling.pt/llms-full.txt): every public docs page in one Markdown file
- Other languages: Português https://outstamp.scaling.pt/pt, Français https://outstamp.scaling.pt/fr, Español https://outstamp.scaling.pt/es