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Email API for Application Integration

EmailEngine provides a comprehensive REST API for email integration. Add email sending, receiving, and management to any application without dealing with IMAP/SMTP protocol complexity.

Email API Features​

Send Emails via API​

Send emails through any provider with a single REST endpoint. EmailEngine handles SMTP connections, OAuth2 authentication, retries, and delivery tracking automatically.

// Send an email with one API call
POST /v1/account/{account}/submit
{
  "to": [{"address": "user@example.com", "name": "John Doe"}],
  "subject": "Hello from EmailEngine",
  "html": "<p>Your message content</p>",
  "attachments": [
    {
      "filename": "report.pdf",
      "content": "base64-encoded-content"
    }
  ]
}

Receive Emails in Real-Time​

Get instant webhook notifications when emails arrive. No polling required - EmailEngine maintains persistent connections to mailboxes and pushes events to your application.

// Webhook payload for new email
{
  "event": "messageNew",
  "data": {
    "id": "AAAAAQAACnA",
    "subject": "Re: Your inquiry",
    "from": {"address": "client@example.com", "name": "Jane Smith"},
    "to": [{"address": "support@yourapp.com"}],
    "text": {"plain": "Thanks for your quick response..."}
  }
}

Manage Email Accounts​

Register and manage multiple email accounts through the API. Support for Gmail, Microsoft 365, and any IMAP/SMTP provider with automatic reconnection and error recovery.

// Register an email account
POST /v1/account
{
  "account": "support-inbox",
  "email": "support@yourcompany.com",
  "imap": {
    "host": "imap.yourprovider.com",
    "port": 993,
    "auth": {
      "user": "support@yourcompany.com",
      "pass": "app-password"
    }
  },
  "smtp": {
    "host": "smtp.yourprovider.com",
    "port": 465,
    "auth": {
      "user": "support@yourcompany.com",
      "pass": "app-password"
    }
  }
}

Search and Organize​

Search messages, manage folders, update flags, and download attachments - all through simple REST API calls.

// Search for emails
GET /v1/account/{account}/search?search[subject]=invoice&search[from]=billing@

// List messages in a folder
GET /v1/account/{account}/messages?path=INBOX&page=0&pageSize=20

// Download attachment
GET /v1/account/{account}/attachment/{attachment}

Why Choose EmailEngine's Email API?​

FeatureEmailEnginePer-Mailbox APIs (Nylas, etc.)
PricingFlat annualPer mailbox/month
Data LocationYour serversThird-party cloud
WebhooksReal-timeReal-time
Account LimitsUnlimitedBased on plan
SetupSelf-hostedManaged service

Cost Comparison​

With per-mailbox pricing (like Nylas at $1.50/mailbox/month):

  • 100 mailboxes = $150/month = $1,800/year
  • 500 mailboxes = $750/month = $9,000/year
  • 1000 mailboxes = $1,500/month = $18,000/year

With EmailEngine's flat pricing, you pay one annual fee regardless of mailbox count.

Compare EmailEngine vs Nylas →

Supported Email Providers​

EmailEngine works with any email service:

  • Gmail & Google Workspace - OAuth2 or Gmail API
  • Microsoft 365 & Outlook.com - OAuth2 or Microsoft Graph API
  • Yahoo Mail - IMAP/SMTP with OAuth2
  • FastMail - IMAP/SMTP
  • ProtonMail - Via ProtonMail Bridge
  • Any IMAP/SMTP server - Standard protocol support

API Capabilities​

Core Operations​

  • Send emails - Single emails, bulk sending, mail merge
  • Receive emails - Real-time webhooks, message listing
  • Search - Full-text and header-based search
  • Attachments - Upload, download, inline images
  • Threading - Conversation tracking (Gmail, Microsoft 365, Yahoo)

Account Management​

  • OAuth2 flows - Built-in authorization for Gmail and Microsoft
  • Connection handling - Automatic reconnection and error recovery
  • Multi-account - Manage thousands of accounts per instance

Advanced Features​

  • Bounce detection - Automatic bounce and complaint handling
  • Delivery tracking - Open and click tracking
  • Templates - Mail merge with variable substitution
  • Scheduling - Delayed sending

Get Started​

1. Install EmailEngine​

# Docker (quickest)
docker run -p 3000:3000 \
  --env EENGINE_REDIS="redis://host.docker.internal:6379/8" \
  postalsys/emailengine:v2

# Or download binary
wget https://go.emailengine.app/emailengine.tar.gz
tar xzf emailengine.tar.gz
./emailengine

Full installation guide →

2. Register an Email Account​

curl -X POST http://localhost:3000/v1/account \
  -H "Content-Type: application/json" \
  -d '{
    "account": "my-account",
    "email": "user@gmail.com",
    "oauth2": {
      "provider": "gmail",
      "auth": {"user": "user@gmail.com"}
    }
  }'

Account setup guide →

3. Send Your First Email​

curl -X POST http://localhost:3000/v1/account/my-account/submit \
  -H "Content-Type: application/json" \
  -d '{
    "to": [{"address": "recipient@example.com"}],
    "subject": "Hello from EmailEngine",
    "text": "This is my first email via the API!"
  }'

Sending guide →

4. Set Up Webhooks​

Configure webhooks to receive real-time notifications:

curl -X POST http://localhost:3000/v1/webhooks \
  -H "Content-Type: application/json" \
  -d '{
    "url": "https://yourapp.com/webhooks/email",
    "events": ["messageNew", "messageSent", "messageDeliveryError"]
  }'

Webhooks guide →

Email API Documentation​

Use Cases​

CRM Email Integration​

Integrate customer email communications directly into your CRM. Track conversations, send follow-ups, and manage relationships. CRM integration guide →

Transactional Email​

Send receipts, notifications, and automated emails from user accounts rather than a shared sending domain. Transactional email guide →

Customer Support​

Build email into your help desk. Manage support inboxes, track threads, and send templated responses. Support integration examples →

AI Email Processing​

Connect email to AI systems for summarization, classification, and automated responses. AI integration guide →

Try EmailEngine Free​

Start with a 14-day free trial - full functionality, no credit card required.

Start Free Trial | View Pricing | GitHub