twilio-sendgrid-account-setup — скилл для Codex: настройка

---
name: twilio-sendgrid-account-setup
description: >
  Set up a SendGrid account for email delivery. Covers API key creation
  (SG.-prefix), domain authentication (DKIM/SPF via CNAME records), Single
  Sender Verification for testing, SDK installation, and the relationship
  between SendGrid and Twilio credentials. Use before any other SendGrid skill.
  This skill is for SendGrid only — not the Twilio Email API (comms.twilio.com).
---

## Overview

SendGrid is Twilio's email delivery engine but uses a **completely separate authentication system** — SendGrid API keys (starting with `SG.`) are not Twilio API keys. You cannot use Account SID/Auth Token for SendGrid, and no Twilio MCP tools wrap SendGrid.

---

## Quickstart

1. Get your API key from [SendGrid Console > Settings > API Keys](https://app.sendgrid.com/settings/api_keys)
2. Set environment variable:

```bash
export SENDGRID_API_KEY=SG.xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
```

3. Install SDK:

| Language | Install | Package |
|----------|---------|---------|
| Python | `pip install sendgrid` | `sendgrid` |
| Node.js | `npm install @sendgrid/mail` | `@sendgrid/mail` (v8.x) |
| Java | Maven | `com.sendgrid:sendgrid-java` |
| C# | `dotnet add package SendGrid` | `SendGrid` |
| Ruby | `gem install sendgrid-ruby` | `sendgrid-ruby` |
| PHP | `composer require sendgrid/sendgrid` | `sendgrid/sendgrid` |
| Go | `go get github.com/sendgrid/sendgrid-go` | `sendgrid-go` |

4. Authenticate your sending domain (see below)

---

## API Key Scopes

| Scope | Use for | Risk |
|-------|---------|------|
| **Full Access** | Development only | Can do everything — never deploy with this |
| **Restricted Access** | Production | Scope to only what your app needs (e.g., Mail Send only) |
| **Billing Access** | Account management | Separate from mail operations |

A "Mail Send" restricted key can send email but cannot read suppressions, manage templates, or access stats. If you get `403 Forbidden`, check key permissions.

---

## SMTP Relay (Alternative to API)

SendGrid also supports SMTP for sending. Useful for frameworks with built-in SMTP support (e.g., Laravel, Django, Rails).

| Setting | Value |
|---------|-------|
| **Server** | `smtp.sendgrid.net` |
| **Port** | `587` (TLS) or `465` (SSL) |
| **Username** | `apikey` (literal string, not your key name) |
| **Password** | Your SendGrid API key (`SG.xxx`) |

---

## Domain Authentication (Required for Production)

Single Sender Verification is for testing only. Production requires domain authentication for deliverability.

**Setup:** SendGrid Console > Settings > Sender Authentication > Authenticate Your Domain

Create 3 CNAME DNS records:
1. `s1._domainkey.yourdomain.com` → `s1.domainkey.u1234.wl.sendgrid.net` (DKIM)
2. `s2._domainkey.yourdomain.com` → `s2.domainkey.u1234.wl.sendgrid.net` (DKIM)
3. `em1234.yourdomain.com` → `u1234.wl.sendgrid.net` (return path)

Verify via API: `GET /v3/whitelabel/domains/{id}/validate`

**DMARC:** After setting up DKIM and SPF via domain authentication, configure a DMARC DNS record (`_dmarc.yourdomain.com`) to instruct receiving servers how to handle authentication failures. Start with `p=none` for monitoring before enforcing.

**Dedicated IP (Pro+ plans):** Isolates your sending reputation. Requires an IP warming schedule — start with low volume and increase over 30 days.

---

## SendGrid and Twilio

| Twilio product | How it uses SendGrid | Sends email? |
|----------------|---------------------|-------------|
| **SendGrid** (this skill) | Direct email delivery via `api.sendgrid.com` | Yes |
| **Twilio Email API** | Direct email delivery via `comms.twilio.com/v1/emails` — uses Twilio creds, not SendGrid keys | Yes (separate product) |
| **Verify** | OTP via `channel: 'email'` | Delegates to SendGrid via Mailer config |
| **Conversations** | Tracks EMAIL as a channel type | No — logs/tracks only |
| **Flex** | Email channel for agents | Uses SendGrid for delivery |

**Servers:**
- Global: `https://api.sendgrid.com`
- EU regional: `https://api.eu.sendgrid.com`

---

## CANNOT

- **Cannot use Twilio credentials for SendGrid** — Separate API keys (`SG.`-prefix), separate Console, separate billing.
- **Cannot access SendGrid via Twilio MCP tools** — No MCP integration. Use SDK or direct REST.
- **Single Sender Verification requires re-verification on address change** — Changing the sender email requires a new verification. Use Domain Authentication for production.
- **Domain Authentication requires DNS access** — 3 CNAME records needed. If you can't modify DNS, you can't authenticate.
- **Domain Authentication API returns stale entries** — `GET /v3/whitelabel/domains` includes old invalid entries. Filter by `valid: true`.
- **API Key Secret shown only at creation** — Cannot retrieve afterward. Store immediately.

> **Security:** Your API key is shown only once at creation. Never display, log, or repeat a user's API key in responses. If a user shares their key in conversation, advise them to rotate it immediately. Store keys in a secrets manager (AWS Secrets Manager, HashiCorp Vault, etc.), not in code or environment files committed to version control.

---

## Next Steps

- **Send email:** `twilio-sendgrid-email-send`
- **Domain settings and templates:** `twilio-sendgrid-email-settings`
- **Delivery tracking:** `twilio-sendgrid-webhooks`
- **Docs:** [SendGrid API Reference](https://www.twilio.com/docs/sendgrid/api-reference)