> For the complete documentation index, see [llms.txt](https://cortex-docs.paloaltonetworks.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://cortex-docs.paloaltonetworks.com/analytics-alerts/alerts-by-name/outbound-email-includes-an-external-bcc-recipient-observed-for-the-first-time.md).
# Outbound email includes an external BCC recipient observed for the first time
### Synopsis
| Field | Value |
| -------------------- | ------------------------------------------------------------------ |
| Activation Period | 14 Days |
| Training Period | 30 Days |
| Test Period | N/A (single event) |
| Deduplication Period | 1 Day |
| Required Data | Microsoft 365 Emails |
| Detection Modules | Email |
| Detector Tags | Exfiltration |
| ATT\&CK Tactic | Execution (TA0002), Credential Access (TA0006) |
| ATT\&CK Technique | User Execution (T1204), Brute Force: Password Cracking (T1110.002) |
| Severity | Informational |
### Description
Internal sender BCC'd an external recipient whose address has not been observed in prior communications.
### Attacker's Goals
Use BCC to covertly exfiltrate data to an unusual external recipient without visibility to other recipients or monitoring systems.
### Investigative actions
* Review headers and content for anomalies or potential exposure of sensitive data.
* Assess the email's context and attack techniques to determine the potential risk.
* Investigate if similar patterns have occurred recently across the organization.
### Variations
Outbound email sent to an unknown external BCC recipient with no To or CC addresses
**Synopsis**
| Field | Value |
| ----------------- | ------------------------------------------------------------------ |
| ATT\&CK Tactic | Execution (TA0002), Credential Access (TA0006) |
| ATT\&CK Technique | User Execution (T1204), Brute Force: Password Cracking (T1110.002) |
| Severity | Low |
**Description**
Internal sender BCC'd an external recipient whose address has not been observed in prior communications.
**Attacker's Goals**
Use BCC to covertly exfiltrate data to an unusual external recipient without visibility to other recipients or monitoring systems.
**Investigative actions**
* Review headers and content for anomalies or potential exposure of sensitive data.
* Assess the email's context and attack techniques to determine the potential risk.
* Investigate if similar patterns have occurred recently across the organization.
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.
Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:
```
GET https://cortex-docs.paloaltonetworks.com/analytics-alerts/alerts-by-name/outbound-email-includes-an-external-bcc-recipient-observed-for-the-first-time.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.