Back to Documentation
Transactional Email API
Complete guide to sending transactional emails with the MailCub API. Learn how to integrate, customize, and optimize your email delivery.
Quick Start
Send Your First Email in 3 Steps
1
Get Your API Key
Sign up for MailCub and generate your API key from the dashboard
2
Verify Your Domain
Add DNS records to verify your sending domain for better deliverability
3
Send Your First Email
Use our API to send your first transactional email
API Examples
curl -X POST https://api.mailcub.com/v1/send \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"to": "user@example.com",
"from": "noreply@yourapp.com",
"subject": "Welcome to our service!",
"html": "<h1>Welcome!</h1><p>Thanks for signing up.</p>",
"text": "Welcome! Thanks for signing up.",
"tags": ["welcome", "onboarding"]
}'Key Features
High-Speed Delivery
Send emails in milliseconds with our optimized SMTP infrastructure
- Sub-second API response times
- Parallel processing for bulk sends
- Global edge network for fast delivery
- Automatic retry mechanisms
Advanced Analytics
Comprehensive tracking and reporting for all your transactional emails
- Real-time delivery tracking
- Open and click analytics
- Bounce and complaint monitoring
- Custom event tracking
Enterprise Security
Bank-level security with authentication and encryption
- TLS 1.3 encryption in transit
- DKIM and SPF authentication
- IP whitelisting and restrictions
- Audit logs and compliance reporting
Developer Experience
Built for developers with comprehensive tools and documentation
- RESTful API with OpenAPI spec
- SDKs for 10+ programming languages
- Webhook support for real-time events
- Testing sandbox environment
Common Use Cases
User Onboarding
- Welcome emails with account setup instructions
- Email verification and confirmation
- Onboarding sequence automation
- Account activation notifications
E-commerce
- Order confirmations and receipts
- Shipping and delivery notifications
- Payment confirmations
- Abandoned cart recovery emails
Security & Authentication
- Password reset instructions
- Two-factor authentication codes
- Login alerts and notifications
- Account security warnings
System Notifications
- Server alerts and monitoring
- Backup completion notifications
- System maintenance updates
- Error and exception reports
Best Practices
Email Content
- Always include both HTML and plain text versions
- Use clear, descriptive subject lines
- Personalize content with user data
- Keep emails concise and actionable
- Include unsubscribe links where required
Deliverability
- Authenticate your sending domain with DKIM/SPF
- Maintain good sender reputation
- Monitor bounce and complaint rates
- Use consistent from addresses
- Avoid spam trigger words and phrases
Performance
- Use templates for consistent formatting
- Batch API calls when sending multiple emails
- Implement proper error handling and retries
- Monitor API rate limits
- Use webhooks instead of polling for status
Rate Limits & Quotas
API Rate Limits
Request Limits
- • Free: 100 requests/hour
- • Starter: 1,000 requests/hour
- • Growth: 10,000 requests/hour
- • Scale: 100,000 requests/hour
Email Quotas
- • Free: 1,000 emails/month
- • Starter: 10,000 emails/month
- • Growth: 100,000 emails/month
- • Scale: 1,000,000 emails/month