Mailbox Agent with Send Authority

A mailbox agent with send authority is an internal artificial intelligence assistant that can read, draft, reply, forward, schedule, route, or send messages on behalf of an employee. Unlike a read-only mailbox assistant, it can act through the employee’s communication identity.

This creates an elevated exposure condition because the assistant combines mailbox access with outbound action. A malicious instruction hidden in an email, attachment, calendar invite, or message thread may cause the synthetic subject to disclose information, forward sensitive content, send unauthorized replies, or route messages externally.

The primary risk is that write and send capability collapses the gap between data exposure and action. A single indirect prompt injection may retrieve sensitive information and transmit it outward. Because messages may be sent under the employee’s identity, the activity can appear authorized, making attribution and containment harder.

A related risk is attributed communication. If the assistant sends or drafts from a named employee’s mailbox, a manipulated response may appear to be that individual’s deliberate statement. This can expose the organization to disputes, claims, regulatory scrutiny, or reputational harm where the response includes an inaccurate commitment, disclosure, approval, or inappropriate language.

Investigators should review the assistant’s directive, mailbox permissions, send authority, forwarding rules, delegated access, logs, retrieved message context, outbound messages, attachments, recipients, and calendar actions. Particular attention should be given to external messages, unusual forwarding, sensitive content in replies, and outbound actions caused by retrieved or embedded instructions.

Investigative Relevance

Mailbox agents with send authority are relevant because they allow a synthetic subject to act through a trusted communication channel. The assistant may expose information, communicate, approve, schedule, or route activity under the apparent authority of an employee.