Isolate Email Streams With Motor Blocks
A Motorical SMTP Motor Block is an isolated sending stream for one project you run, test, or ship (similar to a per-app/per-tenant ESP project): its own domain, auth method, API keys, SMTP credentials, rates, logs, webhooks, and automation. Also known as an SMTP Block. Total control per project.
Use a separate Motor Block for each app, staging vs production, tenant, or domain so unrelated email traffic never shares credentials, rates, logs, or webhook events.
What a Block Separates
Each block can have its own:
- verified sender domain
mk_live_...Motor Block API keys- SMTP credentials
- rate limits and usage counters
- delivery logs and timelines
- webhook endpoints
- operational and deliverability controls
Common Patterns
| Situation | Recommended setup |
|---|---|
| One product with production and staging | One production block and one staging block |
| Multiple apps under one company | One block per app |
| Multiple sending domains | One block per domain |
| Different traffic risk profiles | Separate marketing, transactional, and test streams |
| Tenant-specific domains or webhooks | Separate tenant blocks when isolation matters |
| Legacy app that sends SMTP | SMTP Block for that app |
| Modern backend that sends by API | HTTP Send API with a Motor Block API key |
Example Architecture
Account
├── App A Production Block
│ ├── domain: app-a.example.com
│ ├── auth: mk_live_... + SMTP credentials
│ ├── rates: production policy
│ └── webhooks: https://app-a.example.com/webhooks/motorical
├── App A Staging Block
│ ├── domain: staging-mail.example.com
│ ├── auth: separate test credentials
│ └── webhooks: staging endpoint
└── App B Production Block
├── domain: app-b.example.com
├── auth: independent credentials
└── logs: separate delivery history
Why This Helps
Blocks make email infrastructure easier to reason about:
- A staging bug cannot pollute production analytics.
- A leaked test key does not send from the production block.
- A webhook integration can be tested without receiving production events.
- A high-volume stream can have different rates from transactional mail.
- A tenant or app can be audited through its own logs.
AI Agent Guidance
When an AI assistant designs a Motorical integration, it should ask what boundary matters most:
- application
- environment
- domain
- tenant
- traffic type
- risk level
Then choose the Motor Block that matches that boundary before generating code.