Mimecast Message Tracking

Overview

Message tracking is the primary diagnostic tool in Mimecast for investigating email delivery issues, tracing suspicious messages, and managing held email. The Mimecast MCP server provides tools to search messages across the full delivery pipeline, retrieve detailed per-message metadata, and control message disposition (hold or release). This is the first tool to reach for when investigating reported phishing emails, delivery failures, or missing messages.

Key Concepts

Message States

Held Messages

Messages can be held by Mimecast policy (spam threshold, attachment policy, URL scanning) or placed on hold manually via the API. Held messages require an administrator action — either release them for delivery or permanently delete them.

Message IDs

Each message in Mimecast has:

• Message ID — The RFC 2822 Message-ID header (from the original email)
• Mimecast ID — A Mimecast-internal identifier used for API operations

When searching, you typically use sender/recipient/subject to find messages, then use the Mimecast ID for subsequent operations (get info, hold, release).

API Patterns

Search Messages

mimecast_find_message

Parameters:

• from — Sender email address (supports wildcard, e.g. *@suspicious.com)
• to — Recipient email address
• subject — Subject keyword (partial match supported)
• start — Start datetime (ISO 8601, e.g. 2026-03-01T00:00:00Z)
• end — End datetime (ISO 8601)
• status — Filter by delivery status (delivered, held, rejected, bounced)
• pageToken — Pagination cursor from previous response

Example call:

{
  "from": "phishing@external-domain.com",
  "to": "user@client.com",
  "start": "2026-03-01T00:00:00Z",
  "end": "2026-03-02T23:59:59Z",
  "status": "delivered"
}

Example response:

{
  "meta": {
    "status": 200,
    "pagination": {
      "pageSize": 25,
      "totalCount": 3,
      "next": null
    }
  },
  "data": [
    {
      "id": "eNqrVkpJLU...",
      "messageId": "<abc123@external-domain.com>",
      "from": "phishing@external-domain.com",
      "to": ["user@client.com"],
      "subject": "Your account needs attention",
      "status": "delivered",
      "received": "2026-03-01T14:22:15Z",
      "size": 48293,
      "direction": "inbound"
    }
  ]
}

Get Message Details

mimecast_get_message_info

Parameters:

• id — The Mimecast message ID (from mimecast_find_message response)

Example response:

{
  "meta": { "status": 200 },
  "data": [
    {
      "id": "eNqrVkpJLU...",
      "messageId": "<abc123@external-domain.com>",
      "from": "phishing@external-domain.com",
      "to": ["user@client.com"],
      "subject": "Your account needs attention",
      "status": "delivered",
      "received": "2026-03-01T14:22:15Z",
      "direction": "inbound",
      "senderIP": "192.0.2.45",
      "spamScore": 8,
      "detectionLevel": "relaxed",
      "attachments": [
        {
          "filename": "invoice.pdf",
          "size": 42100,
          "mimeType": "application/pdf"
        }
      ],
      "headers": {
        "X-Originating-IP": "192.0.2.45",
        "Return-Path": "bounce@external-domain.com",
        "Authentication-Results": "spf=fail; dkim=fail; dmarc=fail"
      },
      "route": [
        {
          "action": "smtp_receive",
          "timestamp": "2026-03-01T14:22:14Z",
          "host": "mail.mimecast.com"
        },
        {
          "action": "deliver",
          "timestamp": "2026-03-01T14:22:15Z",
          "host": "mail.client.com"
        }
      ]
    }
  ]
}

Key fields to examine:

• senderIP — Originating IP address of the sender
• spamScore — Mimecast spam scoring (higher = more suspicious)
• headers.Authentication-Results — SPF/DKIM/DMARC authentication results
• route — Full delivery route through the Mimecast pipeline
• attachments — Attached files (names, types, sizes)

Hold a Message

mimecast_hold_message

Places a message on hold to prevent delivery or further routing.

Parameters:

• id — The Mimecast message ID

Example response:

{
  "meta": { "status": 200 },
  "data": [
    {
      "id": "eNqrVkpJLU...",
      "status": "held",
      "heldAt": "2026-03-02T09:15:00Z"
    }
  ]
}

Note: You can only hold messages that are currently in a state that allows it (e.g. processing or delivered to held-queue). Already delivered messages may not be recallable depending on your Mimecast subscription.

Release a Message

mimecast_release_message

Releases a held message for delivery.

Parameters:

• id — The Mimecast message ID

Example response:

{
  "meta": { "status": 200 },
  "data": [
    {
      "id": "eNqrVkpJLU...",
      "status": "released",
      "releasedAt": "2026-03-02T09:20:00Z"
    }
  ]
}

Common Workflows

Investigate a Reported Phishing Email

1. Get sender and approximate send time from the user report
2. Call mimecast_find_message with from, to, and a narrow time range
3. Retrieve the Mimecast message ID from the results
4. Call mimecast_get_message_info to examine:
   • SPF/DKIM/DMARC authentication results
   • Originating IP address
   • Attachment filenames and types
   • Delivery route
5. If message was delivered and is malicious, escalate to threat remediation
6. If message is still in flight, call mimecast_hold_message to stop delivery

Investigate a Missing Email

1. Call mimecast_find_message with sender, recipient, and broad time range
2. If found with held status — message is blocked by policy
3. If found with rejected status — check headers for rejection reason
4. If found with bounced status — the recipient server rejected delivery
5. If not found — the message may not have reached Mimecast (check SPF records)

Release Held Legitimate Email

1. Call mimecast_find_message with status=held to find held messages for a user
2. Call mimecast_get_message_info to verify the message is legitimate
3. Call mimecast_release_message with the message ID
4. Confirm delivery by re-checking status

Domain-Wide Phishing Sweep

1. Call mimecast_find_message with from=*@suspicious-domain.com
2. Use a broad time range (e.g. past 30 days)
3. Identify all recipients who received mail from that domain
4. Cross-reference with TTP logs using mimecast_get_ttp_logs to find URL clicks
5. Notify affected users and escalate to incident response

Error Handling

Message Not Found

Cause: The message ID is invalid, already purged from logs, or outside the retention window. Solution: Mimecast retains message tracking data for 30 days by default. Use mimecast_find_message to search by sender/recipient rather than by ID.

Cannot Hold Message

Cause: Message is already delivered past the hold window, or your subscription does not include message recall. Solution: Use threat remediation tools or advise the user to delete the message manually.

Date Range Too Broad

Cause: Queries without date filters or with very wide date ranges may be rejected or heavily paginated. Solution: Always specify start and end within a reasonable window (7 days or less for efficient queries).

SPF/DKIM Authentication Failure in Headers

Cause: Authentication-Results: spf=fail; dkim=fail indicates the sender is spoofed or the domain is misconfigured. Action: This is a strong phishing indicator. Investigate further and consider blocking the sending domain.

Best Practices

• Always use both from and to wh