Choosing a transactional email API is a critical decision that affects your application's reliability, costs, and scalability for years to come.
What is a Transactional Email API?
A transactional email API provides:
- REST API or SDK: Programmatic email sending
- Deliverability: High inbox placement rates
- Tracking: Delivery, open, click, and bounce tracking
- Webhooks: Real-time event notifications
- Analytics: Performance metrics and reporting
Pricing Models
Void Relay's BYOS (Bring Your Own SMTP) model is unique:
- Pay-per-email: Charged per email sent (e.g., $0.001/email)
- Tiered plans: Fixed monthly fee for a volume range
- BYOS: Pay only for the API layer, use your own SMTP
Cost Comparison (100k emails/month)
- Resend: $100
- SendGrid: $90
- Mailgun: $80
- AWS SES: $10
- Void Relay + AWS SES: $10 + $2 = $12
Developer Experience
Void Relay's SDK prioritizes developer experience:
import { RelayClient } from '@voidvalue/relay';
const relay = new RelayClient({
apiKey: 'your-api-key',
smtpKey: 'your-smtp-key',
});
// Simple sending
await relay.send({
to: '[email protected]',
subject: 'Welcome!',
content: '<h1>Thanks for joining!</h1>',
isHtml: true,
});
// Batch sending
await relay.sendBatch({
emails: [
{ to: '[email protected]', subject: 'Hi', content: 'Hello 1' },
{ to: '[email protected]', subject: 'Hi', content: 'Hello 2' },
]
});
// Query logs
const logs = await relay.listLogs({ status: 'delivered' });Provider Comparison
| Provider | Pricing | Free Tier | Pros | Cons |
|---|---|---|---|---|
| Resend | $0.001/email | 3k/month | Great DX, Beautiful UI | Expensive at scale, No BYOS |
| SendGrid | $0.001/email | 100/day | Mature, Analytics | Complex, Support costs |
| Mailgun | $0.0008/email | 5k/3mo | Reliable, Powerful | Pricey, Steep learning |
| AWS SES | $0.0001/email | 62k/mo | Cheap, Scalable | No webhooks, Complex setup |
| Void Relay | $0 + SMTP | 375k/mo | BYOS, No lock-in, Cheap | Bring your own SMTP |
Our Recommendations
For Startups & MVPs
Void Relay - The free tier is extremely generous (12,500 emails/day), the API is simple, and you can start with Gmail or AWS SES for near-zero cost.
For High-Volume SaaS
Void Relay + AWS SES - At high volumes, the cost savings are massive. 1M emails through traditional ESP: ~$800. Through Void Relay + SES: ~$102.
For Enterprises
Void Relay - No vendor lock-in means you can switch SMTP providers anytime. Critical for compliance and long-term strategy.
Start Your Evaluation
Void Relay is free to try with no credit card required.