Webhook Events Reference

Complete reference for all webhook event types in EmailEngine. Each event includes detailed payload structure, field types, conditional fields, and provider-specific features.

Event Structure

All webhook events follow this common structure:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "eventName",
  "account": "account-id",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    /* event-specific payload */
  }
}

Note: The eventId is NOT included in the JSON payload. It's sent as the HTTP header X-EE-Wh-Event-Id.

Universal Fields

These fields appear in every webhook event JSON payload:

Field	Type	Description
`serviceUrl`	string	Base URL of the EmailEngine instance that generated the event
`event`	string	Event type identifier (e.g., "messageNew", "messageSent")
`account`	string	Account identifier that triggered the event
`date`	string	ISO 8601 timestamp when event occurred
`data`	object	Event-specific payload data

Optional Universal Fields

Field	Type	Description
`path`	string	Mailbox path where the event occurred (message and mailbox events)
`specialUse`	string	Special-use flag of the folder (e.g., "\All", "\Inbox", "\Sent")
`_route`	object	Present when event is delivered through a Webhook Router, contains `_route.id`

Webhook Headers

EmailEngine includes diagnostic headers in every webhook HTTP request:

Header	Type	Example	Description
`X-EE-Wh-Event-Id`	string	`af8435d9-ceee-4715-be71-08ac9d2dc04a`	Unique event identifier (UUID). Use for idempotency - all retries share the same ID. This is the ONLY place eventId is available - it's NOT in the JSON payload.
`X-EE-Wh-Id`	string	`907889`	Internal BullMQ job ID of the queued webhook entry
`X-EE-Wh-Attempts-Made`	string	`0`	Delivery attempt counter (starts at 0, increases with retries)
`X-EE-Wh-Queued-Time`	string	`5s`	Time the event spent in queue before delivery
`X-EE-Wh-Custom-Route`	string	`AAABiL8tBKsAAAAG`	Identifier of the custom webhook route (only present for webhook routes)
`X-EE-Wh-Signature`	string	`dGhpcyBpcyBh...`	HMAC-SHA256 signature (base64url) of the JSON body using EENGINE_SECRET
`Content-Type`	string	`application/json`	Always `application/json`
`User-Agent`	string	`emailengine/2.x.x (+https://emailengine.app)`	EmailEngine version and homepage

Webhook Signature Verification

The X-EE-Wh-Signature header contains an HMAC-SHA256 signature of the request body:

const crypto = require('crypto');

function verifyWebhook(req, secret) {
  const signature = req.headers['x-ee-wh-signature'];
  const body = JSON.stringify(req.body);

  const hmac = crypto.createHmac('sha256', secret);
  hmac.update(body);
  const expected = hmac.digest('base64url');

  return signature === expected;
}

// Usage
if (!verifyWebhook(req, process.env.EENGINE_SECRET)) {
  return res.status(401).json({ error: 'Invalid signature' });
}

You can also configure custom headers via webhooksCustomHeaders in Settings or Configuration → Webhooks.

Account Events

Events related to account connection and status changes.

accountAdded

Triggered when a new account is registered in EmailEngine.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "accountAdded",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "account": "user@example.com"
  }
}

Fields:

data.account (string) - Account identifier

To get the account's display name, email address and connection state after this event, query the account API endpoint (GET /v1/account/:account).

Use Cases:

Send welcome notification
Initialize account-specific resources
Log account creation
Start onboarding flow

accountDeleted

Triggered when an account is removed from EmailEngine.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "accountDeleted",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "account": "user@example.com"
  }
}

Fields:

data.account (string) - Deleted account identifier

Use Cases:

Clean up account-related resources
Remove from billing system
Archive account data
Send farewell notification

accountInitialized

Triggered when an account successfully connects for the first time and completes initial mailbox synchronization.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "accountInitialized",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "initialized": true
  }
}

Fields:

data.initialized (boolean) - Always true, indicates account has completed initialization

Use Cases:

Notify user that account is ready
Start background processing
Enable account features
Trigger initial data import

Note: To get full account details after initialization, query the account API endpoint (GET /v1/account/:account) which returns the account state, connection status, and other metadata.

authenticationError

Triggered when account authentication fails.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "authenticationError",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "response": "Invalid credentials (Failure)",
    "serverResponseCode": "AUTHENTICATIONFAILED"
  }
}

Fields:

data.response (string) - Human-readable error description (often the server's response text)
data.serverResponseCode (string, optional) - Server or error response code (for example AUTHENTICATIONFAILED, or OauthRenewError for OAuth2 accounts)
data.tokenRequest (object, optional) - OAuth2 token-renewal details when the failure occurred while refreshing an access token (includes grant, provider, status, clientId, scopes)

Use Cases:

Prompt user to re-authenticate
Revoke access tokens
Send security alerts
Log authentication failures

authenticationSuccess

Triggered when account authenticates successfully.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "authenticationSuccess",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "user": "user@example.com"
  }
}

Fields:

data.user (string) - The username (login) that authenticated successfully

Use Cases:

Clear authentication error flags
Resume account operations
Log successful authentications
Update account status

connectError

Triggered when connection to the email server fails.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "connectError",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "response": "connect ECONNREFUSED 192.168.1.100:993",
    "serverResponseCode": "ECONNREFUSED"
  }
}

Fields:

data.response (string) - Human-readable connection error description
data.serverResponseCode (string, optional) - Connection error code (for example ECONNREFUSED, ETIMEDOUT, ENOTFOUND)

Use Cases:

Monitor server availability
Trigger network diagnostics
Alert administrators
Log connectivity issues

Message Events

Events related to message operations and changes.

messageNew

Triggered when a new message arrives in any mailbox. Also triggered when messages are moved, copied, or uploaded to folders.

Note: IMAP does not distinguish between incoming messages and messages inserted by other means.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "messageNew",
  "account": "user@example.com",
  "path": "INBOX",
  "specialUse": "\\Inbox",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "id": "AAAABAABNc",
    "uid": 12345,
    "path": "INBOX",
    "emailId": "abc123",
    "threadId": "thread_xyz",
    "date": "2025-01-15T10:25:00.000Z",
    "flags": ["\\Seen"],
    "labels": ["\\Important", "\\Inbox"],
    "category": "primary",
    "unseen": false,
    "flagged": false,
    "answered": false,
    "draft": false,
    "size": 8271,
    "subject": "Important Message",
    "from": {
      "name": "John Doe",
      "address": "john@example.com"
    },
    "sender": {
      "name": "John Doe",
      "address": "john@example.com"
    },
    "replyTo": [
      {
        "name": "John Doe",
        "address": "john@example.com"
      }
    ],
    "to": [
      {
        "name": "Jane Smith",
        "address": "jane@example.com"
      }
    ],
    "cc": [
      {
        "name": "Bob Johnson",
        "address": "bob@example.com"
      }
    ],
    "bcc": [
      {
        "name": "Alice Williams",
        "address": "alice@example.com"
      }
    ],
    "messageId": "<abc123@example.com>",
    "inReplyTo": "<previous@example.com>",
    "headers": {
      "list-id": "<mailinglist.example.com>",
      "x-custom-header": ["value1", "value2"]
    },
    "text": {
      "id": "text_123",
      "encodedSize": {
        "plain": 1535,
        "html": 1630
      },
      "plain": "Message content...",
      "html": "<p>Message content...</p>",
      "webSafe": "<p>Sanitized HTML...</p>",
      "hasMore": false
    },
    "attachments": [
      {
        "id": "att_456",
        "contentType": "application/pdf",
        "filename": "document.pdf",
        "encodedSize": 52341,
        "embedded": false,
        "inline": false,
        "contentId": "<part1.abc@example.com>"
      }
    ],
    "messageSpecialUse": "\\Inbox",
    "seemsLikeNew": true,
    "isAutoReply": false,
    "isBounce": false,
    "isComplaint": false
  }
}

Core Fields:

data.id (string) - EmailEngine message ID (use for API operations)
data.uid (number) - IMAP UID
data.path (string) - Mailbox path
data.emailId (string, optional) - RFC 8474 Email ID (Gmail, modern IMAP servers)
data.threadId (string, optional) - Thread/conversation ID (Gmail, modern IMAP servers)
data.date (string) - Message Date header (ISO 8601)
data.flags (array of strings) - IMAP flags (e.g., "\Seen", "\Flagged", "\Answered", "\Draft")
data.unseen (boolean) - Message is unread (no \Seen flag)
data.flagged (boolean) - Message is flagged
data.answered (boolean) - Message has been replied to
data.draft (boolean) - Message is a draft
data.size (number) - Full RFC 822 message size in bytes
data.subject (string) - Email subject line
data.messageId (string) - RFC 5322 Message-ID header
data.inReplyTo (string, optional) - Message-ID of the message being replied to

Address Fields:

Each address object contains:

name (string) - Display name
address (string) - Email address

Fields:

data.from (object) - Sender address
data.sender (object, optional) - Actual sender (when different from From)
data.replyTo (array of objects, optional) - Reply-To addresses
data.to (array of objects) - Recipients
data.cc (array of objects, optional) - CC recipients
data.bcc (array of objects, optional) - BCC recipients

Content Fields (Conditional):

Included when Configuration → Webhooks → Email Content is enabled (notifyText: true):

data.text (object, optional) - Message text content
- data.text.id (string) - Text content identifier
- data.text.encodedSize (object) - Size information
  - data.text.encodedSize.plain (number) - Plain text size in bytes
  - data.text.encodedSize.html (number) - HTML size in bytes
- data.text.plain (string) - Plain text content (up to notifyTextSize limit)
- data.text.html (string) - HTML content (up to notifyTextSize limit)
- data.text.webSafe (string, optional) - Sanitized HTML (when notifyWebSafeHtml: true)
- data.text.hasMore (boolean) - Content was truncated

Attachment Fields (Conditional):

Included when Configuration → Webhooks → Attachments is enabled (notifyAttachments: true):

data.attachments (array of objects, optional) - Attachment metadata
- id (string) - Attachment identifier
- contentType (string) - MIME type
- filename (string) - Filename
- encodedSize (number) - Size of the attachment as stored in the email (base64 encoded); the decoded file size is approximately 75% of this value
- embedded (boolean, optional) - Is embedded image
- inline (boolean, optional) - Is inline attachment
- encodedInMessage (boolean, optional) - Whether the attachment belongs to an enclosed message/rfc822 part rather than the top-level message
- contentId (string, optional) - Content-ID header value
- method (string, optional) - Calendar method (REQUEST, REPLY, CANCEL, etc.) for iCalendar attachments

Gmail-Specific Fields:

data.labels (array of strings, optional) - Gmail labels (e.g., "\Important", "\Inbox", "\Starred")
data.category (string, optional) - Gmail category tab ("primary", "social", "promotions", "updates", "forums")
- Requires Configuration → Email Processing → Gmail Features → Detect Gmail Categories enabled
data.messageSpecialUse (string, optional) - Special-use flag that best classifies the message (prefer over top-level specialUse)

Header Fields (Conditional):

Included when headers are specified in notifyHeaders setting:

data.headers (object, optional) - Requested email headers
- Keys are lowercase header names
- Values are strings or arrays for multi-value headers

Metadata Fields:

data.seemsLikeNew (boolean, optional) - EmailEngine has no prior record of this message (~99% accuracy)
data.isAutoReply (boolean, optional) - Message appears to be an auto-reply
data.isBounce (boolean, optional) - Message appears to be a bounce
data.isComplaint (boolean, optional) - Message appears to be an abuse complaint

AI Feature Fields (Conditional):

Included when AI features are enabled:

data.summary (object, optional) - AI-generated analysis (when generateEmailSummary: true). Contains summary (text), sentiment, shouldReply (boolean), events (array), actions (array), plus generation metadata (id, tokens, model)
data.embeddings (array of numbers, optional) - Vector embeddings (when openAiGenerateEmbeddings: true)
data.riskAssessment (object, optional) - AI risk analysis
- data.riskAssessment.risk (integer) - Risk score where a higher value indicates higher risk
- data.riskAssessment.assessment (string) - Human-readable explanation of the risk score
- data.riskAssessment.id (string, optional) - Generation identifier
- data.riskAssessment.tokens (number, optional) - Tokens consumed generating the assessment

Use Cases:

Real-time email notifications
Auto-reply systems
Email-to-ticket conversion
Message classification
Attachment processing
Email analytics
Spam filtering
Thread management

Example Integration:

app.post('/webhook', async (req, res) => {
  const event = req.body;
  const eventId = req.headers['x-ee-wh-event-id'];

  if (event.event === 'messageNew') {
    const { data } = event;

    // Check idempotency using header
    if (await isProcessed(eventId)) {
      return res.json({ success: true }); // Already handled
    }

    // Notify user
    await sendPushNotification({
      title: `New email from ${data.from.address}`,
      body: data.subject
    });

    // Process attachments
    if (data.attachments?.length > 0) {
      await processAttachments(data.id, data.attachments);
    }

    // Auto-classify
    if (data.subject?.includes('invoice')) {
      await moveToFolder(data.id, 'Invoices');
    }

    // Mark as processed
    await markProcessed(eventId);
    res.json({ success: true });
  }
});

messageDeleted

Triggered when a message is deleted from a mailbox or moved to another folder.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "messageDeleted",
  "account": "user@example.com",
  "path": "INBOX",
  "specialUse": "\\Inbox",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "id": "AAAABAABNc",
    "uid": 12345
  }
}

Fields:

path (string) - Mailbox path the message was deleted from (top-level field, alongside account)
specialUse (string, optional) - Special-use flag of that mailbox (top-level field)
data.id (string) - EmailEngine message ID
data.uid (number) - IMAP UID (no longer valid)

For IMAP accounts the data object contains only id and uid. Gmail API and Microsoft Graph accounts include provider-specific fields (for example Gmail adds threadId and the last known labels). See messageDeleted for the per-provider payloads.

Use Cases:

Sync deletions to local database
Track deleted messages
Compliance logging
Undo deletion feature
Analytics (deletion patterns)

messageUpdated

Triggered when message flags or labels change (read/unread, flagged, etc.).

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "messageUpdated",
  "account": "user@example.com",
  "path": "INBOX",
  "specialUse": "\\Inbox",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "id": "AAAABAABNc",
    "uid": 12345,
    "changes": {
      "flags": {
        "added": ["\\Seen"],
        "removed": [],
        "value": ["\\Seen", "\\Flagged"]
      },
      "labels": {
        "added": ["\\Important"],
        "removed": ["\\Inbox"],
        "value": ["\\Important", "\\Starred"]
      }
    }
  }
}

Fields:

path (string) - Mailbox path (top-level field, alongside account)
specialUse (string, optional) - Special-use flag of that mailbox (top-level field)
data.id (string) - EmailEngine message ID
data.uid (number) - IMAP UID
data.changes (object) - Change details
- data.changes.flags (object) - Flag changes
  - data.changes.flags.added (array of strings) - Newly added flags
  - data.changes.flags.removed (array of strings) - Removed flags
  - data.changes.flags.value (array of strings) - Current complete flag list
- data.changes.labels (object, optional) - Label changes (Gmail)
  - data.changes.labels.added (array of strings) - Newly added labels
  - data.changes.labels.removed (array of strings) - Removed labels
  - data.changes.labels.value (array of strings) - Current complete label list

Use Cases:

Sync read status across devices
Track flag changes
Update UI in real-time
Analytics (read rates)
Trigger workflows on status changes

messageMissing

Triggered when a previously seen message is no longer found in the mailbox (may indicate external deletion or mailbox corruption).

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "messageMissing",
  "account": "user@example.com",
  "path": "INBOX",
  "specialUse": "\\Inbox",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "id": "AAAABAABNc",
    "uid": 12345,
    "missingRetries": 5,
    "missingDelay": 12450
  }
}

Fields:

path (string) - Mailbox path (top-level field, alongside account)
specialUse (string, optional) - Special-use flag of that mailbox (top-level field)
data.id (string) - EmailEngine message ID
data.uid (number) - IMAP UID (no longer valid)
data.missingRetries (number, optional) - Number of resynchronization attempts made before the message was reported missing
data.missingDelay (number, optional) - Delay in milliseconds before the message was confirmed missing

Use Cases:

Detect sync issues
Alert on potential data loss
Trigger resynchronization
Debugging mailbox problems

Mailbox Events

Events related to mailbox (folder) operations.

mailboxNew

Triggered when a new mailbox (folder) is created.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "mailboxNew",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "path": "Projects/2025",
    "name": "2025",
    "specialUse": false,
    "uidValidity": "1697551353"
  }
}

Fields:

data.path (string) - Full mailbox path
data.name (string) - Mailbox name (last component of path)
data.specialUse (string or false) - Special-use flag (e.g., "\Sent", "\Drafts", "\Trash"), or false when the folder has no special use
data.uidValidity (string) - The folder's UIDVALIDITY value (sent as a string)

Use Cases:

Sync folder structure
Update folder lists
Track folder organization
Folder-based automation rules

mailboxDeleted

Triggered when a mailbox (folder) is deleted.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "mailboxDeleted",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "path": "Old/Archive",
    "name": "Archive",
    "specialUse": false
  }
}

Fields:

data.path (string) - Deleted mailbox path
data.name (string) - Mailbox name
data.specialUse (string or false) - Special-use flag, or false when the folder has no special use

Use Cases:

Remove folder from UI
Archive folder contents
Cleanup folder-based rules

mailboxReset

Triggered when the UIDVALIDITY of a folder changes. This indicates the folder was deleted and recreated, or the server reset its UID namespace.

Important: All previous UIDs for this folder are now invalid. You should refetch all messages.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "mailboxReset",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "path": "INBOX",
    "name": "INBOX",
    "specialUse": "\\Inbox",
    "uidValidity": "1234567899",
    "prevUidValidity": "1234567890"
  }
}

Fields:

data.path (string) - Mailbox path that was reset
data.name (string) - Mailbox name (last component of path)
data.specialUse (string or false) - Special-use flag of the folder, or false when it has no special use
data.uidValidity (string) - New UIDVALIDITY value (sent as a string)
data.prevUidValidity (string) - Previous UIDVALIDITY value (sent as a string)

Use Cases:

Invalidate cached message UIDs
Trigger full mailbox resynchronization
Update local database
Clear message references

Sending Events

Events related to sending emails.

messageSent

Triggered when a message is successfully accepted by the mail server (MTA).

Note: This indicates the server accepted the message, not that it was delivered to recipients. See messageBounce for delivery failures.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "messageSent",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "messageId": "<abc123@example.com>",
    "originalMessageId": "<original123@example.com>",
    "response": "250 2.0.0 Ok: queued as ABC123",
    "queueId": "queue_456",
    "envelope": {
      "from": "sender@example.com",
      "to": ["recipient@example.com"]
    }
  }
}

Fields:

data.messageId (string) - Final Message-ID (may be rewritten by server)
data.originalMessageId (string, optional) - Original Message-ID when the server rewrites it (Amazon SES, AWS WorkMail, Microsoft Graph)
data.response (string) - The mail server's response to the message submission (typically the full SMTP 250 line)
data.queueId (string) - Internal queue identifier
data.envelope (object) - SMTP envelope
- data.envelope.from (string) - Envelope sender (MAIL FROM)
- data.envelope.to (array of strings) - Envelope recipients (RCPT TO)
data.networkRouting (object, optional) - Present only when a custom local address or proxy was used; may contain localAddress, proxy, name, and requestedLocalAddress

There is no to, subject, or gateway field in this payload - the recipients are in envelope.to. To correlate the event with the original send, match on queueId (or messageId).

Message-ID Rewriting:

Some mail servers (Amazon SES, AWS WorkMail, Microsoft Graph) replace the Message-ID header. When this happens:

messageId contains the final server-assigned ID
originalMessageId contains your original ID

Always use messageId for tracking - it's the ID stored on the server.

Use Cases:

Confirm delivery to user
Update sent status in database
Track email campaigns
Delivery analytics
Trigger follow-up actions

Example Integration:

if (event.event === 'messageSent') {
  const { data } = event;

  // Update database
  await db.emails.updateOne(
    { queueId: data.queueId },
    { $set: { status: 'sent', messageId: data.messageId } }
  );

  // Notify user
  await notifyUser({
    message: `Message ${data.messageId} sent successfully`
  });

  // Analytics
  await trackEvent('email_sent', {
    account: event.account,
    recipients: data.envelope.to.length
  });
}

messageDeliveryError

Triggered when email sending fails. EmailEngine retries automatically. You receive one webhook per failed attempt.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "messageDeliveryError",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "queueId": "queue_456",
    "envelope": {
      "from": "sender@example.com",
      "to": ["invalid@example.com"]
    },
    "messageId": "<abc123@example.com>",
    "error": "Recipient address rejected: User unknown",
    "errorCode": "EPROTOCOL",
    "smtpResponse": "550 5.1.1 <invalid@example.com>: Recipient address rejected: User unknown",
    "smtpResponseCode": 550,
    "smtpCommand": "RCPT TO",
    "job": {
      "id": "42",
      "attemptsMade": 1,
      "attempts": 10,
      "nextAttempt": "2025-01-15T10:07:45.465Z"
    }
  }
}

Fields:

data.queueId (string) - Internal queue ID
data.envelope (object) - SMTP envelope
- data.envelope.from (string) - Envelope sender
- data.envelope.to (array of strings) - Envelope recipients
data.messageId (string) - Message-ID header
data.error (string) - Error message
data.errorCode (string) - Error code (e.g., "EPROTOCOL", "ECONNECTION", "EAUTH")
data.smtpResponse (string, optional) - Full SMTP error response from the server
data.smtpResponseCode (number, optional) - Numeric SMTP response code
data.smtpCommand (string, optional) - SMTP command that triggered the error (for example RCPT TO)
data.networkRouting (object, optional) - Present only when a custom local address or proxy was used
data.job (object) - Queue job status
- data.job.id (string) - BullMQ job identifier
- data.job.attemptsMade (number) - Current attempt number
- data.job.attempts (number) - Maximum attempts (default 10)
- data.job.nextAttempt (string) - ISO 8601 timestamp of next retry

There is no to, subject, or response field in this payload - recipients are in envelope.to and the server response text is in smtpResponse.

Common SMTP Error Codes:

550 5.1.1 - User unknown / mailbox not found
550 5.7.1 - Relay denied / not authorized
552 5.2.2 - Mailbox full
554 5.7.1 - Message rejected (spam)

Use Cases:

Alert user to sending failure
Update failed status
Custom retry logic
Bounce handling
Email validation

messageFailed

Triggered when EmailEngine abandons delivery after all retry attempts fail. This is a permanent failure.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "messageFailed",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "messageId": "<abc123@example.com>",
    "queueId": "queue_456",
    "error": "Error: Invalid login: 535 5.7.8 Error: authentication failed",
    "networkRouting": {
      "localAddress": "192.168.1.100"
    }
  }
}

Fields:

data.messageId (string) - Message-ID header
data.queueId (string) - Internal queue ID
data.error (string) - Final error message (first line of stack trace)
data.networkRouting (object, optional) - Present only when a custom local address or proxy was used; may contain localAddress, proxy, name, and requestedLocalAddress

Use Cases:

Notify sender of permanent failure
Remove from send queue
Log failed deliveries
Update campaign statistics
Trigger alternative delivery methods

messageBounce

Triggered when a bounce (DSN - Delivery Status Notification) message is received for a sent email.

Note: Field coverage depends on the bounce format and what EmailEngine can parse. Different mail servers provide different levels of detail.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "messageBounce",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "bounceMessage": "AAAAAQAABWw",
    "recipient": "bounced@example.com",
    "action": "failed",
    "response": {
      "source": "smtp",
      "message": "550 5.1.1 <bounced@example.com>: Recipient address rejected: User unknown in relay recipient table",
      "status": "5.1.1",
      "category": "user_unknown",
      "recommendedAction": "remove"
    },
    "mta": "mx.example.com",
    "queueId": "BFC608226A",
    "messageId": "<abc123@example.com>",
    "messageHeaders": {
      "from": ["sender@example.com"],
      "to": ["bounced@example.com"],
      "subject": ["Newsletter"],
      "message-id": ["<abc123@example.com>"]
    }
  }
}

Fields:

data.bounceMessage (string) - EmailEngine ID of the bounce message itself
data.recipient (string, optional) - Bounced recipient address
data.action (string) - DSN action ("failed", "delayed", "delivered", "relayed", "expanded")
data.response (object, optional) - Parsed bounce response
- data.response.source (string, optional) - Source of the diagnostic code (e.g., "smtp")
- data.response.message (string, optional) - Bounce message
- data.response.status (string, optional) - Enhanced status code (e.g., "5.1.1")
- data.response.category (string, optional) - ML-classified bounce category (see table below)
- data.response.recommendedAction (string, optional) - Suggested action: "remove", "retry", "review", "fix_configuration", "retry_different_ip", or "remove_content"
- data.response.blocklist (object, optional) - Blocklist details when the bounce indicates a blocklist issue
  - data.response.blocklist.name (string) - Blocklist name (e.g., "Spamhaus ZEN")
  - data.response.blocklist.type (string) - "ip" or "domain"
- data.response.retryAfter (number, optional) - Suggested retry delay in seconds (when timing found in error message)
data.mta (string, optional) - Reporting Mail Transfer Agent hostname
data.queueId (string, optional) - MTA queue identifier (Postfix-specific)
data.messageId (string, optional) - Original Message-ID that bounced
data.messageHeaders (object, optional) - Headers parsed from the original bounced message (keys are lowercased header names, values are arrays)

ML Bounce Categories:

EmailEngine uses machine learning to classify bounces into detailed categories:

Category	Description	Action
`user_unknown`	Recipient doesn't exist	remove
`invalid_address`	Bad syntax or domain not found	remove
`mailbox_disabled`	Account suspended/disabled	remove
`mailbox_full`	Over quota	retry
`greylisting`	Temporary rejection	retry
`rate_limited`	Too many connections	retry
`server_error`	Timeout/connection failed	retry
`ip_blacklisted`	Sender IP on blocklist	retry_different_ip
`domain_blacklisted`	Sender domain on blocklist	fix_configuration
`auth_failure`	DMARC/SPF/DKIM failure	fix_configuration
`relay_denied`	Relaying not permitted	fix_configuration
`spam_blocked`	Detected as spam	review
`policy_blocked`	Local policy rejection	review
`virus_detected`	Infected content	remove_content
`geo_blocked`	Geographic rejection	retry_different_ip
`unknown`	Unclassified	review

Permanent vs temporary failures:

The payload does not include a bounceType field. Use action (failed indicates a permanent failure, delayed a temporary one) together with response.status (a 5.x.x enhanced status code is permanent, 4.x.x is temporary) and response.recommendedAction to decide how to handle the bounce.

Use Cases:

Remove permanently failed recipients (action: "failed") from mailing lists
Retry temporary failures based on recommendedAction and retryAfter
Detect and respond to blocklist issues
Email validation
Delivery reporting
Maintain sender reputation
Compliance with anti-spam regulations

Handling Multiple Recipients:

If a message sent to multiple recipients bounces for several addresses, EmailEngine emits a separate messageBounce event for each recipient.

messageComplaint

Triggered when an ARF (Abuse Reporting Format) feedback loop complaint is received. This indicates a recipient marked your email as spam.

Note: Field coverage depends on the reporting provider. Some providers omit headers like Message-ID.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "messageComplaint",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "complaintMessage": "AAAAAQAABvE",
    "arf": {
      "source": "Hotmail",
      "feedbackType": "abuse",
      "abuseType": "complaint",
      "originalRcptTo": ["recipient@hotmail.co.uk"],
      "arrivalDate": "2021-10-22T13:04:36.017Z",
      "sourceIp": "1.2.3.4",
      "userAgent": "Mozilla/5.0..."
    },
    "headers": {
      "messageId": "<abc123@example.com>",
      "from": "sender@example.com",
      "to": ["recipient@hotmail.co.uk"],
      "subject": "Newsletter",
      "date": "2021-10-22T16:04:33.000Z"
    }
  }
}

Fields:

data.complaintMessage (string) - EmailEngine ID of the complaint message
data.arf (object) - ARF feedback loop data
- data.arf.source (string, optional) - Provider name (e.g., "Hotmail", "Yahoo")
- data.arf.feedbackType (string) - Feedback type ("abuse", "fraud", "virus", "not-spam")
- data.arf.abuseType (string, optional) - Specific abuse type
- data.arf.originalMailFrom (string, optional) - Envelope sender of the original email
- data.arf.originalRcptTo (array of strings, optional) - Original recipients
- data.arf.arrivalDate (string, optional) - When complaint was generated (ISO 8601)
- data.arf.sourceIp (string, optional) - IP address that sent the original email
- data.arf.userAgent (string, optional) - User agent string
data.headers (object, optional) - Original message headers (may be incomplete)
- data.headers.messageId (string, optional) - Message-ID of complained message
- data.headers.from (string, optional) - From address
- data.headers.to (array of strings, optional) - Recipients
- data.headers.subject (string, optional) - Subject line
- data.headers.date (string, optional) - Date header

Use Cases:

Remove complainers from mailing lists immediately
Investigate spam complaints
Improve email content
Monitor sender reputation
Compliance with anti-spam laws (CAN-SPAM, GDPR)
Alert administrators

Tracking Events

Events related to email tracking (opens and clicks).

Note: Tracking requires Configuration → Email Processing → Email Tracking to be enabled.

trackOpen

Triggered when a tracking pixel embedded in an email is requested, indicating the recipient opened the email.

Warning: False positives are possible when:

Webmail clients cache linked images
Email clients pre-fetch images
Security software scans emails

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "trackOpen",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "messageId": "<abc123@example.com>",
    "remoteAddress": "203.0.113.45",
    "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.83 Safari/537.36"
  }
}

Fields:

data.messageId (string) - Message-ID of the opened email
data.remoteAddress (string) - IP address that requested the tracking pixel
data.userAgent (string) - User-Agent header from the request

Use Cases:

Track email open rates
Engagement analytics
Campaign performance
Follow-up timing
A/B testing

trackClick

Triggered when a tracked link in an email is clicked.

Warning: False positives may occur when:

Security software pre-fetches URLs
Link scanners check URLs for safety
Email clients preview links

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "trackClick",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "messageId": "<abc123@example.com>",
    "url": "https://example.com/page",
    "remoteAddress": "203.0.113.45",
    "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.83 Safari/537.36"
  }
}

Fields:

data.messageId (string) - Message-ID of the email containing the link
data.url (string) - Original URL that was clicked
data.remoteAddress (string) - IP address of the clicker
data.userAgent (string) - User-Agent header from the request

Use Cases:

Track click-through rates
Identify popular content
Engagement metrics
Conversion tracking
Link performance analysis

List Management Events

Events related to email list subscriptions and unsubscriptions.

listUnsubscribe

Triggered when a recipient clicks the List-Unsubscribe link or when an email client issues a one-click unsubscribe request (RFC 8058).

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "listUnsubscribe",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "recipient": "recipient@example.com",
    "messageId": "<abc123@example.com>",
    "listId": "my-newsletter-list",
    "remoteAddress": "203.0.113.45",
    "userAgent": "Mozilla/5.0..."
  }
}

Fields:

data.recipient (string) - Email address being unsubscribed
data.messageId (string) - Message-ID of the email that contained the unsubscribe link
data.listId (string, optional) - List identifier (from List-ID header)
data.remoteAddress (string, optional) - IP address of the request
data.userAgent (string, optional) - User-Agent header

Use Cases:

Remove from mailing list immediately
Send unsubscribe confirmation
Update preference center
Compliance (CAN-SPAM, GDPR)
Analytics (unsubscribe rates)

listSubscribe

Triggered when a recipient resubscribes to a list after previously unsubscribing.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "listSubscribe",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "recipient": "recipient@example.com",
    "listId": "my-newsletter-list",
    "remoteAddress": "203.0.113.45",
    "userAgent": "Mozilla/5.0..."
  }
}

Fields:

data.recipient (string) - Email address being resubscribed
data.listId (string, optional) - List identifier
data.remoteAddress (string, optional) - IP address of the request
data.userAgent (string, optional) - User-Agent header

Use Cases:

Add to mailing list
Send welcome-back email
Update preference center
Analytics (resubscribe rates)

Export Events

Events related to bulk message export operations. See Exporting Messages for details on the export feature.

exportCompleted

Triggered when a bulk message export completes successfully.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "exportCompleted",
  "account": "user@example.com",
  "date": "2025-01-15T10:35:00.000Z",
  "data": {
    "exportId": "exp_abc123def456abc123def456",
    "folders": ["INBOX", "Sent"],
    "startDate": "2024-01-01T00:00:00.000Z",
    "endDate": "2024-12-31T23:59:59.000Z",
    "messagesExported": 450,
    "messagesSkipped": 5,
    "bytesWritten": 52428800,
    "duration": 15000,
    "expiresAt": "2025-01-16T10:30:00.000Z"
  }
}

Fields:

data.exportId (string) - Export job identifier (28-character format: exp_ + 24 hex digits)
data.folders (array of strings) - Folders that were exported
data.startDate (string) - Start of export date range (ISO 8601)
data.endDate (string) - End of export date range (ISO 8601)
data.messagesExported (number) - Total messages successfully exported
data.messagesSkipped (number) - Messages skipped (deleted or inaccessible during export)
data.bytesWritten (number) - Total bytes written to export file
data.duration (number) - Export processing time in milliseconds
data.expiresAt (string) - When the export file expires (ISO 8601)

Use Cases:

Notify user that export is ready for download
Trigger automated download workflows
Log export completion for auditing
Update export job status in your application

exportFailed

Triggered when a bulk message export fails.

Payload:

{
  "serviceUrl": "https://emailengine.example.com",
  "event": "exportFailed",
  "account": "user@example.com",
  "date": "2025-01-15T10:30:00.000Z",
  "data": {
    "exportId": "exp_abc123def456abc123def456",
    "error": "Connection timeout",
    "errorCode": "ConnectionTimeout",
    "phase": "exporting",
    "messagesExported": 250,
    "messagesQueued": 1500
  }
}

Fields:

data.exportId (string) - Export job identifier
data.error (string) - Error message describing the failure
data.errorCode (string, optional) - Error code for programmatic handling
data.phase (string) - Phase when failure occurred ("indexing" or "exporting")
data.messagesExported (number) - Messages exported before failure
data.messagesQueued (number) - Total messages that were queued for export

Use Cases:

Notify user of export failure
Retry export operation
Log failures for debugging
Alert administrators of persistent failures

Complete Event List

Quick reference table of all events:

Event	Category	Trigger	Common Use
`accountAdded`	Account	Account registered	Onboarding
`accountDeleted`	Account	Account removed	Cleanup
`accountInitialized`	Account	First successful sync	Enable features
`authenticationError`	Account	Auth failed	Re-authenticate
`authenticationSuccess`	Account	Auth succeeded	Resume operations
`connectError`	Account	Connection failed	Monitor connectivity
`messageNew`	Message	New message received	Notifications
`messageDeleted`	Message	Message deleted	Sync deletions
`messageUpdated`	Message	Flags changed	Sync read status
`messageMissing`	Message	Message disappeared	Debugging
`messageSent`	Sending	Email accepted by MTA	Confirm delivery
`messageDeliveryError`	Sending	Send failed (retry)	Alert & retry
`messageFailed`	Sending	Send failed (permanent)	Log failure
`messageBounce`	Sending	Bounce received	List management
`messageComplaint`	Sending	FBL complaint	Remove from list
`trackOpen`	Tracking	Email opened	Analytics
`trackClick`	Tracking	Link clicked	Engagement
`listUnsubscribe`	List	Unsubscribed	Remove from list
`listSubscribe`	List	Resubscribed	Add to list
`mailboxNew`	Mailbox	Folder created	Sync folders
`mailboxDeleted`	Mailbox	Folder deleted	Update UI
`mailboxReset`	Mailbox	UIDVALIDITY changed	Resync folder
`exportCompleted`	Export	Export job completed	Download export
`exportFailed`	Export	Export job failed	Retry/alert

Event Filtering

Subscribe to specific events when configuring webhooks:

{
  "webhooks": "https://your-app.com/webhook",
  "webhookEvents": [
    "messageNew",
    "messageSent",
    "messageDeliveryError"
  ]
}

Common Combinations:

Basic email monitoring:

["messageNew", "messageDeleted"]

Sending tracking:

["messageSent", "messageDeliveryError", "messageFailed", "messageBounce"]

Full monitoring:

[
  "messageNew",
  "messageDeleted",
  "messageUpdated",
  "messageSent",
  "messageDeliveryError",
  "messageFailed",
  "messageBounce",
  "messageComplaint",
  "trackOpen",
  "trackClick",
  "listUnsubscribe",
  "authenticationError",
  "connectError"
]

Subscribe to all events: Use ["*"] to receive all events.

Conditional Fields Reference

Many fields only appear under specific conditions:

Configuration-Dependent Fields

Text Content (notifyText: true):

data.text.plain
data.text.html
data.text.webSafe (also requires notifyWebSafeHtml: true)
data.text.hasMore

Attachments (notifyAttachments: true):

data.attachments[]

Custom Headers (notifyHeaders: ["Header-Name"]):

data.headers

AI Features:

data.summary (requires generateEmailSummary: true)
data.embeddings (requires openAiGenerateEmbeddings: true)

Provider-Specific Fields

Gmail:

data.labels - Gmail labels
data.category - Inbox category (requires "Resolve Gmail categories" enabled)
data.emailId - Gmail Email ID
data.threadId - Gmail Thread ID

Outlook/Modern IMAP:

data.emailId - RFC 8474 Email ID
data.threadId - Thread ID

Message-Dependent Fields

Optional Headers:

data.cc - Only when CC recipients exist
data.bcc - Only when BCC recipients exist
data.replyTo - Only when Reply-To differs from From
data.sender - Only when Sender differs from From
data.inReplyTo - Only for reply messages

Metadata:

data.seemsLikeNew - Only for messageNew events
data.isAutoReply - Only when detected
data.isBounce - Only when detected
data.isComplaint - Only when detected

Gmail-Specific Features

Labels vs Flags

Gmail uses labels instead of traditional IMAP flags. EmailEngine provides both:

data.flags - IMAP flags (limited set)
data.labels - Full Gmail label list (recommended)

Common Gmail labels:

\Inbox - In inbox
\Important - Marked important
\Starred - Starred
\Sent - Sent mail
\Drafts - Draft messages
\Trash - In trash
UNREAD - Unread (alternative to lack of \Seen flag)

Category Tabs

Enable Configuration → Email Processing → Gmail Features → Detect Gmail Categories to get:

data.category - One of: "primary", "social", "promotions", "updates", "forums"

Special Use Folders

For Gmail, prefer data.messageSpecialUse over top-level specialUse:

specialUse is usually "\All" (all mail)
data.messageSpecialUse indicates the logical folder (e.g., "\Inbox")

Email ID and Thread ID

Gmail provides stable identifiers:

data.emailId - Unique message identifier (survives moves)
data.threadId - Conversation identifier (groups related messages)

Outlook-Specific Features

Folder Structure

Outlook uses "/" as delimiter. Common folders:

INBOX - Inbox
Sent Items - Sent mail
Drafts - Drafts
Deleted Items - Trash
Junk Email - Spam

Shared Mailboxes

Events from shared mailboxes include the same fields. Use account to identify which mailbox.

Feature	Gmail Labels	Outlook Categories
Pre-creation required	Yes - must exist in Gmail	No - auto-created when set
Folder mapping	Yes - labels map to folders	No - separate tag system
Backend support	Gmail IMAP, Gmail API	Microsoft Graph API only
Color support	No colors	Colors assigned by Outlook (not via API)
Delete/rename via API	Yes	No - use Outlook directly

AI Features

When AI features are enabled (OpenAI integration):

Email Summary

Enable: generateEmailSummary: true

Adds: data.summary (object) - AI-generated analysis of the email content

Example:

{
  "data": {
    "subject": "Q4 Sales Report",
    "summary": {
      "id": "chatcmpl-7IzVIEp5UL3hdQ3aZJ8AHyrJrt3R0",
      "tokens": 2060,
      "model": "gpt-4",
      "sentiment": "neutral",
      "summary": "Sales increased 23% in Q4. Top performers: Product A (+45%), Product B (+12%). Request for Q1 strategy meeting.",
      "shouldReply": true,
      "events": [],
      "actions": [
        { "description": "Schedule Q1 strategy meeting", "dueDate": "2025-01-31" }
      ]
    }
  }
}

data.summary is an object, not a plain string. The human-readable text is in data.summary.summary.

Vector Embeddings

Enable: openAiGenerateEmbeddings: true

Adds: data.embeddings (array of numbers) - Vector representation for semantic search

Example use:

// Find similar emails
const similar = await findSimilar(message.embeddings, threshold: 0.8);

Risk Assessment

Adds: data.riskAssessment (object) - AI-powered risk analysis

{
  "data": {
    "riskAssessment": {
      "id": "chatcmpl-7IzVIEp5UL3hdQ3aZJ8AHyrJrt3R0",
      "tokens": 320,
      "risk": 7,
      "assessment": "The sender domain does not match the reply-to address and the message contains an urgent payment request."
    }
  }
}

risk is an integer where a higher value indicates higher risk; assessment is a human-readable explanation. There is no score or reasons field.

Event Handling Best Practices

Idempotency

Always handle duplicate events using the X-EE-Wh-Event-Id header:

const processedEvents = new Set();

app.post('/webhook', async (req, res) => {
  const event = req.body;
  const eventId = req.headers['x-ee-wh-event-id'];

  // Check idempotency
  if (processedEvents.has(eventId)) {
    console.log('Duplicate event, skipping');
    return res.json({ success: true });
  }

  // Or use database
  const exists = await db.events.findOne({ eventId });
  if (exists) {
    return res.json({ success: true }); // Already processed
  }

  // Process event
  await processEvent(event);

  // Mark as processed
  await db.events.insertOne({ eventId, processed: true });
  processedEvents.add(eventId);

  res.json({ success: true });
});

Error Handling

Return 2xx status for successful processing, 5xx to trigger retry:

app.post('/webhook', async (req, res) => {
  try {
    await processWebhook(req.body);
    res.json({ success: true });
  } catch (error) {
    console.error('Webhook error:', error);
    // Return 5xx to trigger EmailEngine retry
    res.status(500).json({ error: error.message });
  }
});

Async Processing

Queue webhooks for background processing to respond quickly:

app.post('/webhook', async (req, res) => {
  // Queue immediately
  await queue.add('webhook', req.body);

  // Respond quickly (< 5 seconds recommended)
  res.json({ success: true });
});

// Process in background
queue.process('webhook', async (job) => {
  await processWebhook(job.data);
});

Handling Conditional Fields

Check for field existence before accessing:

function processMessageNew(event) {
  const { data } = event;

  // Safe text access
  if (data.text?.plain) {
    await indexText(data.text.plain);
  }

  // Safe attachment access
  if (data.attachments?.length > 0) {
    await processAttachments(data.attachments);
  }

  // Gmail-specific
  if (data.labels?.includes('\\Important')) {
    await flagAsImportant(data.id);
  }

  // AI features
  if (data.summary) {
    await storeSummary(data.id, data.summary);
  }
}

Event-Specific Handling

Use switch statements for clarity:

async function processWebhook(event) {
  switch (event.event) {
    case 'messageNew':
      return handleNewMessage(event.account, event.data);

    case 'messageSent':
      return handleMessageSent(event.account, event.data);

    case 'messageDeliveryError':
      return handleSendError(event.account, event.data);

    case 'messageBounce':
      return handleBounce(event.account, event.data);

    case 'messageComplaint':
      return handleComplaint(event.account, event.data);

    case 'trackOpen':
      return handleOpen(event.account, event.data);

    case 'trackClick':
      return handleClick(event.account, event.data);

    case 'listUnsubscribe':
      return handleUnsubscribe(event.account, event.data);

    case 'accountError':
      return handleAccountError(event.account, event.data);

    default:
      console.log('Unhandled event:', event.event);
  }
}

Webhook Retry Handling

EmailEngine retries failed webhooks up to 10 times with exponential backoff:

app.post('/webhook', async (req, res) => {
  const attemptNumber = parseInt(req.headers['x-ee-wh-attempts-made'] || '1');
  const eventId = req.headers['x-ee-wh-event-id'];

  if (attemptNumber > 1) {
    console.log(`Retry attempt ${attemptNumber} for event ${eventId}`);
  }

  // Process webhook...
  await processEvent(req.body);

  res.json({ success: true });
});

Webhook Retry Mechanism

EmailEngine automatically retries failed webhook deliveries:

Maximum attempts: 10
Backoff formula: delay = 5000ms × 2^(attempt - 1)
Retry delays:
- Attempt 1: Immediate
- Attempt 2: 5 seconds
- Attempt 3: 10 seconds
- Attempt 4: 20 seconds
- Attempt 5: 40 seconds
- Attempt 6: 80 seconds (1.3 minutes)
- Attempt 7: 160 seconds (2.7 minutes)
- Attempt 8: 320 seconds (5.3 minutes)
- Attempt 9: 640 seconds (10.7 minutes)
- Attempt 10: 1280 seconds (21.3 minutes)

After 10 failed attempts, the webhook is marked as undeliverable and moved to the Failed queue.

Monitor webhooks:

Dashboard: System → Queues → notify
Pending retries: Delayed section
Undeliverable: Failed section

Configure retention:

Configuration → General → Queue Management
Set retention limits for completed/failed jobs

Testing Events

Using Webhook Tailing

Real-time webhook monitoring in the EmailEngine UI:

Navigate to Configuration → Webhooks
Click Tail Webhooks
Trigger events (send email, receive email, change flags)
See events in real-time with full payloads

Using Webhook Testing Services

Test webhooks without implementing an endpoint:

Webhook.site - Inspect payloads, headers, test responses
RequestBin - Create temporary endpoints
ngrok - Expose local server for testing

Example ngrok setup:

# Start local server
node server.js

# Expose via ngrok
ngrok http 3000

# Use ngrok URL in EmailEngine webhook settings
https://abc123.ngrok.io/webhook

Testing Specific Events

Test messageNew: Send email to the account

Test messageSent: Use Send API

Test messageDeliveryError: Send to invalid address

Test messageBounce: Send to known bounce address

Test trackOpen: Enable tracking, send email, open it

Test trackClick: Enable tracking, send email with link, click it

Test listUnsubscribe: Add List-Unsubscribe header, click unsubscribe

Event Structure​

Universal Fields​

Optional Universal Fields​

Webhook Headers​

Webhook Signature Verification​

Account Events​

accountAdded​

accountDeleted​

accountInitialized​

authenticationError​

authenticationSuccess​

connectError​

Message Events​

messageNew​

messageDeleted​

messageUpdated​

messageMissing​

Mailbox Events​

mailboxNew​

mailboxDeleted​

mailboxReset​

Sending Events​

messageSent​

messageDeliveryError​

messageFailed​

messageBounce​

messageComplaint​

Tracking Events​

trackOpen​

trackClick​

List Management Events​

listUnsubscribe​

listSubscribe​

Export Events​

exportCompleted​

exportFailed​

Complete Event List​

Event Filtering​

Conditional Fields Reference​

Configuration-Dependent Fields​

Provider-Specific Fields​

Message-Dependent Fields​

Gmail-Specific Features​

Labels vs Flags​

Category Tabs​

Special Use Folders​

Email ID and Thread ID​

Outlook-Specific Features​

Folder Structure​

Shared Mailboxes​

Categories​

AI Features​

Email Summary​

Vector Embeddings​

Risk Assessment​

Event Handling Best Practices​

Idempotency​

Error Handling​

Async Processing​

Handling Conditional Fields​

Event-Specific Handling​

Webhook Retry Handling​

Webhook Retry Mechanism​

Testing Events​

Using Webhook Tailing​

Using Webhook Testing Services​

Testing Specific Events​

Event Structure

Universal Fields

Optional Universal Fields

Webhook Headers

Webhook Signature Verification

Account Events

accountAdded

accountDeleted

accountInitialized

authenticationError

authenticationSuccess

connectError

Message Events

messageNew

messageDeleted

messageUpdated

messageMissing

Mailbox Events

mailboxNew

mailboxDeleted

mailboxReset

Sending Events

messageSent

messageDeliveryError

messageFailed

messageBounce

messageComplaint

Tracking Events

trackOpen

trackClick

List Management Events

listUnsubscribe

listSubscribe

Export Events

exportCompleted

exportFailed

Complete Event List

Event Filtering

Conditional Fields Reference

Configuration-Dependent Fields

Provider-Specific Fields

Message-Dependent Fields

Gmail-Specific Features

Labels vs Flags

Category Tabs

Special Use Folders

Email ID and Thread ID

Outlook-Specific Features

Folder Structure

Shared Mailboxes

Categories

AI Features

Email Summary

Vector Embeddings

Risk Assessment

Event Handling Best Practices

Idempotency

Error Handling

Async Processing

Handling Conditional Fields

Event-Specific Handling

Webhook Retry Handling

Webhook Retry Mechanism

Testing Events

Using Webhook Tailing

Using Webhook Testing Services

Testing Specific Events