# SendGrid

> SendGrid (a Twilio company) is a cloud-based email delivery platform providing reliable transactional and marketing email over an HTTP v3 REST API and SMTP relay. This llms.txt was GENERATED by the API Evangelist enrichment pipeline from the SendGrid catalog (apis.yml) and the artifacts in this repository, as a SendGrid-scoped index. All APIs authenticate with a bearer API key against https://api.sendgrid.com (EU data residency host: https://api.eu.sendgrid.com).
>
> PROVIDER-PUBLISHED llms.txt (re-checked 2026-08-13): SendGrid's documentation host DOES serve a real llms.txt at https://www.twilio.com/docs/llms.txt — 1,892 lines covering every Twilio product, including a "## Twilio SendGrid" section of 340 entries linking each SendGrid API-reference page as markdown. It is saved verbatim in this repo at llms/sendgrid-twilio-docs-llms.txt. The 2026-06-20 pass recorded "SendGrid does not publish its own llms.txt", which was wrong: sendgrid.com/llms.txt returns HTTP 200 but with a 611KB HTML SPA shell (a soft-200, not a document), and www.twilio.com/docs/sendgrid/llms.txt returns 404 — the real file lives one level up at the docs root. Prefer the provider's file for authoritative page links; prefer this file for the SendGrid-only view and the artifact index below.

## APIs
- [Mail Send v3 API](https://www.twilio.com/docs/sendgrid/api-reference/mail-send): Send transactional email at scale over HTTP.
- [Marketing Campaigns Contacts API](https://www.twilio.com/docs/sendgrid/api-reference/contacts): Manage marketing contacts, imports, exports, and search.
- [Marketing Campaigns Lists API](https://www.twilio.com/docs/sendgrid/api-reference/lists): Manage static contact lists.
- [Marketing Campaigns Segments 2.0 API](https://www.twilio.com/docs/sendgrid/api-reference/segmenting-contacts-v2): Dynamic audience segments.
- [Marketing Campaigns Single Sends API](https://www.twilio.com/docs/sendgrid/api-reference/single-sends): One-time marketing email sends.
- [Transactional Templates API](https://www.twilio.com/docs/sendgrid/api-reference/transactional-templates): Manage dynamic email templates and versions.
- [Suppressions API](https://www.twilio.com/docs/sendgrid/api-reference/suppressions-unsubscribe-groups): Manage bounces, blocks, spam reports, and unsubscribe groups.
- [Email Activity API](https://www.twilio.com/docs/sendgrid/api-reference/email-activity): Query stored message activity.
- [Email Address Validation API](https://www.twilio.com/docs/sendgrid/api-reference/email-address-validation): Real-time email address validity (Pro/Premier).
- [Statistics API](https://www.twilio.com/docs/sendgrid/api-reference/stats): Aggregated email program statistics.
- [Domain Authentication API](https://www.twilio.com/docs/sendgrid/api-reference/domain-authentication): SPF/DKIM sender domain authentication.
- [API Keys API](https://www.twilio.com/docs/sendgrid/api-reference/api-keys): Manage API keys and their scopes.
- [Subusers API](https://www.twilio.com/docs/sendgrid/api-reference/subusers-api): Multi-tenant sub-account management.
- [Webhooks Configuration API](https://www.twilio.com/docs/sendgrid/api-reference/webhooks): Event and Inbound Parse webhooks.

## Specs
- [OpenAPI specs (44)](https://github.com/api-evangelist/sendgrid/tree/main/openapi): One OpenAPI 3.x definition per product API (tsg_*_v3.yaml).
- [AsyncAPI: Event Webhook](https://raw.githubusercontent.com/api-evangelist/sendgrid/refs/heads/main/asyncapi/sendgrid-event-webhook-asyncapi.yml): Event delivery webhook.
- [AsyncAPI: Inbound Parse](https://raw.githubusercontent.com/api-evangelist/sendgrid/refs/heads/main/asyncapi/sendgrid-inbound-parse-asyncapi.yml): Inbound email parse webhook.
- [Arazzo workflows (20)](https://github.com/api-evangelist/sendgrid/tree/main/arazzo): Native multi-step workflows over SendGrid operations.
- [Postman collections (44)](https://github.com/api-evangelist/sendgrid/tree/main/postman): One collection per product API.

## Docs
- [Developer documentation](https://www.twilio.com/docs/sendgrid): Full SendGrid developer docs.
- [API reference](https://www.twilio.com/docs/sendgrid/api-reference): Complete v3 API reference.
- [Getting started](https://www.twilio.com/docs/sendgrid/for-developers/sending-email/api-getting-started): API quickstart.
- [Authentication](https://www.twilio.com/docs/sendgrid/for-developers/sending-email/authentication): Bearer API key authentication.
- [Rate limits](https://www.twilio.com/docs/sendgrid/api-reference/how-to-use-the-sendgrid-v3-api/rate-limits): X-RateLimit headers and 429 behavior.
- [Errors](https://www.twilio.com/docs/sendgrid/api-reference/how-to-use-the-sendgrid-v3-api/errors): HTTP status codes and error envelope.
- [Sandbox mode](https://www.twilio.com/docs/sendgrid/for-developers/sending-email/sandbox-mode): Validate mail-send requests without delivery.
- [Pricing](https://sendgrid.com/en-us/pricing): Plans and pricing.
- [Status page](https://status.sendgrid.com/): Service status.
- [Libraries / SDKs](https://www.twilio.com/docs/sendgrid/for-developers/sending-email/libraries): Official helper libraries (Python, Node.js, Java, C#, Go, Ruby, PHP).