Outlook is one of the biggest exit doors for sensitive data in any company. Employees email SSNs, card numbers, patient records, and credential-laden attachments every day. Microsoft's native Outlook/Purview DLP can flag some of it, but it does not truly redact the data, it is gated behind expensive E5 licensing, and it is noisy. Strac adds a data layer to Outlook: it detects PII, PHI, and PCI inside message bodies and attachments, redacts or masks the sensitive values, blocks forwarding to unauthorized external addresses, and logs every access for your HIPAA, PCI, and SOC 2 auditors. It is agentless and installs as a Microsoft 365 app in minutes.
Email is still where sensitive data goes to leak. A support rep pastes a customer's Social Security Number into a reply. A nurse forwards a patient intake PDF to a personal Gmail account. A finance analyst attaches a spreadsheet of card numbers "just to get it approved fast." None of it is malicious. All of it is a reportable incident.
For most companies, that email runs through Microsoft Outlook. This guide covers what Data Loss Prevention (DLP) for Outlook actually needs to do in 2026, where Microsoft's native controls stop short, and how Strac detects and remediates sensitive data in Outlook emails and attachments.
Strac inspects the email body and every attachment, identifies PII/PHI/PCI, and redacts the sensitive values before the message is delivered or read. The original stays in an encrypted vault for authorized access, and every action is logged.
Outlook is not just a chat surface. It carries structured, high-value regulated data, usually inside attachments that native tools never open:
The attachment problem is the one that gets companies breached. A message body can look clean while a 12-page PDF attached to it contains dozens of SSNs. Any Outlook DLP worth deploying has to open and inspect the attachment, not just the text.
Microsoft does ship DLP for Outlook through Microsoft Purview. It is real, and for some organizations it is a reasonable first layer. But teams consistently hit the same walls:
The result: sensitive data is detected sometimes, but rarely remediated, and the burden of tuning falls on an already-stretched security team.
Strac adds the missing data layer to Outlook. It installs as a native Microsoft 365 app (agentless, no gateway, no MX record changes) and runs four jobs:
Strac's classifiers scan the message body and open every attachment, including PDFs, Office files, and images via built-in OCR. It ships with hundreds of prebuilt detectors and lets you define your own custom data elements for company-specific identifiers.
This is the difference that matters. Instead of blocking the whole email, Strac redacts the SSN or card number in place and keeps the rest of the message intact and useful. The original sensitive value is tokenized and stored in an encrypted vault, retrievable only by authorized roles. Read more on why we lead with remediation, not just detection.
Strac can prevent a sensitive email from being forwarded to personal or unapproved external domains, closing the most common exfiltration path, without stopping legitimate internal collaboration.
Every detection, redaction, and access event is logged. When an auditor asks "show me you control PHI in email," you have the evidence instead of a policy document.
Outlook data does not only leak through the Outlook client. In 2026 there are two paths to worry about:
A DLP tool that only watches the Outlook client misses both of these. Strac watches the data wherever it moves.
Microsoft 365 Copilot is now embedded directly in Outlook. It drafts replies, summarizes threads, and pulls context from across the mailbox. That is genuinely useful, and it is also a new way for PHI and PII to be surfaced, summarized, and copied into places your DLP policies never covered.
Copilot respects existing permissions, but most mailboxes are over-permissioned and full of years of unredacted sensitive data. If that data was never cleaned up, Copilot can now surface it instantly. Strac's approach is to redact the sensitive data at the source so that whatever Copilot (or a human) retrieves is already clean. This is the same data-layer wedge we apply across AI data security.
Email is explicitly in scope for every major framework:
Because Strac is agentless, there is nothing to install on endpoints for the email use case. You connect the Microsoft 365 / Outlook app, choose which sensitive data elements to detect, and pick the action per data type (redact, mask, block external forward, or audit-only). Most teams are live the same day. Pair it with Strac's endpoint and browser DLP to cover the human path across every other app, and you have one console for your whole data loss prevention program.
Yes, through Microsoft Purview DLP, which can detect sensitive data and apply policy tips or blocks in Outlook. The catch is that its strongest capabilities require E5-tier licensing, it warns rather than truly redacting the sensitive value, and its attachment/image coverage is inconsistent. Most teams use it as a baseline and add a dedicated tool like Strac for redaction and attachment inspection.
Yes. Strac detects PII, PHI, and PCI in the message body and inside attachments (PDF, Office files, and images via OCR), then redacts or masks the sensitive values in place while keeping the rest of the email usable. The original is stored encrypted for authorized retrieval.
No. Strac connects as a Microsoft 365 app and works independently of your Microsoft licensing tier, so you get redaction and attachment scanning without upgrading to E5.
Yes. Strac can block a sensitive email from being forwarded to unauthorized external addresses while still allowing legitimate internal collaboration, closing one of the most common exfiltration paths.
Copilot can surface any sensitive data already sitting in an over-permissioned mailbox. Strac reduces that risk by redacting sensitive data at the source, so what Copilot retrieves is already clean. See our Microsoft Copilot DLP guide.
The data-protection model is the same, the surface differs. If you run Google Workspace instead, see Gmail DLP and Google Workspace DLP.
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