SentraMind
← All crew Design-partner roadmap M3 Email & Channel DLP

Postmaster

Checks outbound mail for possible internal or accidental data disclosure before it leaves, then later the file share, the USB port and the print queue.

What changes for the organisation

The wrong attachment to the wrong recipient stops being a notifiable breach.

How it works

Body, recipients, headers, conversation context and supported attachments are analysed before delivery. Deterministic detectors and policy decide the clear cases; the private LLM judges the ambiguous ones. Outcomes are allow, warn, quarantine for authorised review, hard-block, or require approval.

What it watches
  • Outgoing email first — body, recipients, headers, thread context, supported attachments
  • Later channel adapters: file shares, USB, print — all inheriting the same policy, evidence, incident and audit controls
  • Recipient signals: personal, newly observed, lookalike and otherwise inappropriate domains
Mail-platform coverage

Ten on-premises mail-server families, one governed analysis contract

Design-partner roadmap

The planned SMTP relay and transport-agent path is designed for customer-operated mail infrastructure. Each named platform remains subject to connector validation, capacity testing and the design-partner promotion gates stated on this page.

  • Microsoft Exchange Server
  • HCL Domino
  • Zimbra Collaboration
  • Postfix
  • Exim
  • Zextras Carbonio
  • IceWarp Server
  • MDaemon Email Server
  • Kerio Connect
  • Axigen Mail Server
01

Other in-house mail systems

Where a customer operates another mail server or a non-standard routing topology, SentraMind can provide connector-customisation services to map its hold, analysis, decision, release and evidence behaviours onto that environment.

02

Hosted mail and client extensions

For hosted services such as Gmail, Outlook.com or Yahoo Mail, a browser extension or an Outlook client add-in can apply a similar pre-send data-disclosure check. Coverage depends on the host and client extension points available to the customer.

03

DLP scope, not malware scanning

Postmaster looks for possible data disclosure: sensitive content sent outside policy, to an inappropriate recipient, or exposed internally to people without entitlement. Antivirus, malicious attachment and malware scanning remain with existing specialist security products.

End-to-end operating flow

How the email-scan agent crew works

Every step has a bounded responsibility and authority. Rules handle clear cases first, the private model judges only the remaining ambiguity, and an authorised person controls release.

01 · Observe

A user composes and sends an email

Body, recipients, headers, thread context and supported attachments

02 · Hold

Pause the message before delivery

The message has not crossed the governed boundary.

04 · Detect deterministically

Look for possible data disclosure

Sensitive data, Exact Data Match, document fingerprints, credentials, wrong or unentitled recipients, and lookalike domains.

Ambiguous cases only

Private model judges bounded context

The model does not receive the mailbox and cannot authorise release.

05 · Governed decision

Policy combines authoritative signals and model contribution

Explicit rules always win; every decision leaves a reason and evidence.

Allow Deliver safely
Warn Let the sender correct it
Approval Authorised person decides
Quarantine Reviewer releases, returns or blocks
Hard-block Stop policy-breaking delivery
06 · Evidence

Record analysis, hold, decision, review and terminal state

Sensitive content is not echoed to the sender; reveals and releases are attributed to authorised people.

Authoritative rule / system Private-model contribution Human decision Existing security tool
How it actually works

The mechanism, not the marketing. If a step below would not survive an engineer's scrutiny, it should not be on this page.

1
The message is held before it leaves the boundary
Adapter-specific: an on-premises transport agent or an SMTP relay hop routes outbound mail through the common channel-analysis contract pre-delivery. This runs on the asynchronous plane — the latency budget is seconds, and it never touches the 150 ms verdict path reserved for enforcement.
2
The MIME tree is decomposed
Plaintext body, HTML body, headers, and every attachment are separated and handled independently, so an evasion that hides content in one part does not bypass analysis of the others.
3
Attachments never touch the model
Text extraction runs in isolated specialist parsers with active content disabled, inside a sandbox separated from the model runtime, the tool gateway, the control plane and the evidence store. Existing specialist security products continue to scan for viruses and malware.
4
Deterministic detectors run on body and extracted text
The same checksum country-ID packs, secret patterns, Exact Data Match and document fingerprinting used by the prompt path — one detection stack, one tuning effort, one set of false positives to manage.
5
Every recipient is classified
Internal, known external, personal-domain, newly-observed — first contact from this organisation — or lookalike, by edit distance against your own and your counterparties' domains. This is the layer that catches the wrong recipient, which no content detector can.
6
Context is judged only for what remains ambiguous
Header consistency across From, Reply-To and Return-Path; thread continuity checked against actual mail history rather than the claimed conversation; payment-instruction language; bank details compared against historical values; bulk-forward anomalies.
7
Five outcomes, and one of them is a person
Allow, warn the sender, quarantine for an authorised reviewer, hard-block, or require approval. The sender's explanation names the category and never quotes the content back.

Operating path

From signal to auditable evidence

Roadmap

01Observed inputs

  • Outgoing email first — body, recipients, headers, thread context, supported attachments
  • Later channel adapters: file shares, USB, print — all inheriting the same policy, evidence, incident and audit controls
  • Recipient signals: personal, newly observed, lookalike and otherwise inappropriate domains

02Deterministic workflow

  1. 1 The message is held before it leaves the boundary Adapter-specific: an on-premises transport agent or an SMTP relay hop routes outbound mail through the common channel-analysis contract pre-delivery. This runs on the asynchronous plane — the latency budget is seconds, and it never touches the 150 ms verdict path reserved for enforcement.
  2. 2 The MIME tree is decomposed Plaintext body, HTML body, headers, and every attachment are separated and handled independently, so an evasion that hides content in one part does not bypass analysis of the others.
  3. 3 Attachments never touch the model Text extraction runs in isolated specialist parsers with active content disabled, inside a sandbox separated from the model runtime, the tool gateway, the control plane and the evidence store. Existing specialist security products continue to scan for viruses and malware.
  4. 4 Deterministic detectors run on body and extracted text The same checksum country-ID packs, secret patterns, Exact Data Match and document fingerprinting used by the prompt path — one detection stack, one tuning effort, one set of false positives to manage.
  5. 5 Every recipient is classified Internal, known external, personal-domain, newly-observed — first contact from this organisation — or lookalike, by edit distance against your own and your counterparties' domains. This is the layer that catches the wrong recipient, which no content detector can.
  6. 6 Context is judged only for what remains ambiguous Header consistency across From, Reply-To and Return-Path; thread continuity checked against actual mail history rather than the claimed conversation; payment-instruction language; bank details compared against historical values; bulk-forward anomalies.
  7. 7 Five outcomes, and one of them is a person Allow, warn the sender, quarantine for an authorised reviewer, hard-block, or require approval. The sender's explanation names the category and never quotes the content back.

03Evidence outputs

  • M0-schema events for every analysis, hold, release and block
  • Quarantine and release decisions attributed to the authorising reviewer
  • Breach-notification fields aligned to per-jurisdiction clocks
This diagram describes the specified workflow; the maturity label states its current delivery status.
A case

The attachment that was one hidden worksheet from a notifiable breach

Not an attacker. A relationship manager in a hurry, on a Friday afternoon.

16:48
Q3_review.xlsx is attached and sent to a client contact. The message is held pre-delivery; the sender's client shows it as sending.
16:48:03
The workbook is extracted in the sandbox. A third worksheet, hidden and not visible in the sender's view, contains 1,340 rows belonging to a different client.
16:48:04
62 Exact Data Match hits against the enrolled customer table. The recipient is known-external and legitimate — but not entitled to that data.
16:48:05
Outcome: quarantine for authorised review. The sender sees a warning naming the category only. No content is echoed, because a sender who is about to make a mistake is not a reason to show them someone else's data.
16:52
The reviewer opens the case, sees the masked evidence under their own role, confirms it, and returns the message to the sender for correction.
Recorded
One quarantine, one authorised review with the reveal logged, one release-to-sender. Nothing crossed the boundary, so no notification clock started.
What it came to

Had it delivered, this was a personal-data disclosure to an unauthorised third party. Malaysia's PDPA 72-hour clock and the client's own contractual notification terms would both have been running from the moment it was discovered — which, realistically, would have been weeks later.

How a decision gets made

The authority ladder. Green rungs are authoritative — a rule, a scanner, a sandbox, or a person. Blue is where the model contributes. Amber is where a human decides.

01
Authoritative signal
The same data-leak detector stack as Sentry, plus recipient, mail-authentication and reputation signals. Existing antivirus and malware-security tools retain responsibility for malicious-file detection.
02
Bounded context
The model receives the authorised message context needed for the judgement — not the mailbox.
03
Model contribution
Contextual judgement on ambiguity: recipient and content mismatch, apparently accidental wrong recipient, impersonation, urgent payment instruction, conversation hijacking, changed bank details.
04
Policy and reviewer
Quarantine releases require an authorised reviewer. Explanations never echo sensitive content.

What the model adds

Judgement on the cases a rule cannot describe — the business-email-compromise pattern, the attachment that is wrong for this recipient, the thread that changed tone.

What it cannot claim

It cannot confirm a compromise or authorise a release. It flags, explains, and hands the decision to a person.

What it will never do
  • Never releases quarantined mail without an authorised reviewer.
  • Never lets the LLM open an attachment. Text extraction is done by isolated specialist parsers; virus and malware detection remains the responsibility of the organisation's existing security tools.
  • Never echoes sensitive content in an explanation shown to the sender.
  • Never becomes a mail gateway of record. It calls the common channel-analysis contract and emits the M0 event schema.
What evidence it leaves
  • M0-schema events for every analysis, hold, release and block
  • Quarantine and release decisions attributed to the authorising reviewer
  • Breach-notification fields aligned to per-jurisdiction clocks
See it work
Not built

A specification, not a simulation

We will not show you a scripted demonstration of something that does not exist. What we publish instead is the workflow specification, held to the same standard as shipped work: actor, trigger, happy path, exceptions, terminal state, and the audit evidence it must leave. When it is built, this section becomes a demonstration.

Status and what promotion requires

Roadmap discovery. Promotion requires two design partners, a named mail-platform connector passing its support contract, mail-processing latency and quarantine/release accuracy targets, a capacity profile, a threat model and architecture approval.

Roles that touch it

End UserPolicy AdminReviewer / ApproverSOC Analyst