---
title: Developer documentation | SendHQ Docs
description: "Build with the SendHQ email API: sending, receiving, domains, templates, deliverability, suppressions, billing, and complete endpoint reference."
canonical: https://sendhq.cc/docs
last-updated: 2026-09-07
---
# Email infrastructure with explicit outcomes.

Verify a domain, send expected email, receive replies, publish typed templates, and inspect delivery without hiding provider state.

[Send my first email](https://sendhq.cc/docs/quickstart.md) [API reference](https://sendhq.cc/docs/api-reference.md)

```shell
curl https://sendhq.cc/api/v1/emails \
  -H "Authorization: Bearer $SENDHQ_API_KEY" \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: welcome-user-42" \
  -d '{"from":"Acme <hello@example.com>","to":["customer@example.net"],"subject":"Welcome","text":"Your workspace is ready."}'
```

## Start with the job you need to ship.

- [01](https://sendhq.cc/docs/sending.md): Send expected email Single requests, batches, replies, attachments, retries, and delivery events.
- [02](https://sendhq.cc/docs/templates.md): Publish reusable templates Typed variables, optimistic drafts, exact previews, tests, and immutable releases.
- [03](https://sendhq.cc/docs/inbound.md): Receive and thread replies Inbound addresses, retained messages, private attachments, and conversations.
- [04](https://sendhq.cc/docs/mcp.md): Connect an AI agent Run the SendHQ MCP server with Claude Code, Codex, or Claude Desktop: 59 typed tools with safety labels.

## Follow the full system, not an isolated request.

- [Start here](https://sendhq.cc/docs/quickstart.md): Quickstart Create a key, verify a domain, and send a controlled email with a retry-safe request.
- [Start here](https://sendhq.cc/docs/resend-migration.md): Migrate from Resend Map Resend HTTP sends to SendHQ and account for the compatibility boundaries before cutover.
- [Start here](https://sendhq.cc/docs/authentication.md): Authentication Use server-side API keys for product integrations and browser sessions for workspace administration.
- [Start here](https://sendhq.cc/docs/errors.md): Errors and retries Parse the standard JSON error envelope and decide when a retry is safe.
- [Start here](https://sendhq.cc/docs/versioning.md): Versioning and deprecation Understand major URL versions, compatible additions, deprecation notices, and sunset windows.
- [Send](https://sendhq.cc/docs/sending.md): Sending email Send transactional messages, batches, replies, attachments, and hosted templates safely.
- [Send](https://sendhq.cc/docs/domains.md): Domains and DNS Provision sender identities and interpret DNS, SES, propagation, and repair states.
- [Send](https://sendhq.cc/docs/templates.md): Hosted templates Create typed drafts, preview exact output, publish immutable releases, and preserve send provenance.
- [Receive](https://sendhq.cc/docs/inbound.md): Inbound email Create inboxes, receive routed messages, retain attachments, and build chronological conversations.
- [Receive](https://sendhq.cc/docs/labels.md): Labels and buckets File sent and received mail into labels automatically, and give an agent a bucket its conversations never leave.
- [Receive](https://sendhq.cc/docs/inbox-sorting.md): Spam, updates, and importance How SendHQ sorts received mail into primary, updates, and spam, flags important messages, and learns from corrections.
- [Operate](https://sendhq.cc/docs/deliverability.md): Deliverability Understand provider events, sender-identity reputation, daily ramping, and automatic recovery.
- [Operate](https://sendhq.cc/docs/suppressions.md): Suppressions and opt-outs Prevent unsafe delivery to bounced, complained, or unsubscribed recipients.
- [Operate](https://sendhq.cc/docs/billing.md): Billing and limits Understand trial restrictions, recipient credits, attachment transfer, and webhook-driven entitlements.
- [Tools](https://sendhq.cc/docs/cli.md): Command-line interface Install the SendHQ CLI to send and read email, verify domains, manage inboxes and templates, and run the MCP server from a terminal, a script, or CI.
- [Integrations](https://sendhq.cc/docs/supabase-auth-emails.md): Supabase Auth emails Send Supabase sign-up, magic link, password reset, and email change messages through SendHQ with Supabase's Send Email hook and an Edge Function.

## OpenAPI 3.1, generated from the same catalog as these pages.

Use the specification for clients, testing, discovery, and agent tooling.

[Open specification](https://sendhq.cc/openapi.json) [Browse endpoints](https://sendhq.cc/docs/api-reference.md)