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14/07/2026 4:20 pm
TL;DR: A regional financial institution found that strengthening Microsoft Purview DLP exposed broader blind spots in internal email visibility, lateral phishing, and data exfiltration workflows, according to Proofpoint. The lesson is that DLP projects fail when email security, investigation speed, and data protection operate as separate control planes.
NHIMG editorial — based on content published by Proofpoint: a regional financial institution's evaluation of Microsoft Purview DLP and email security visibility
By the numbers:
- 72% of organisations have experienced or suspect they have experienced a breach of non-human identities, 46% confirmed and 26% suspected.
- When AWS credentials are exposed publicly, attackers attempt access within an average of 17 minutes and as quickly as 9 minutes in some cases.
Questions worth separating out
Q: What breaks when DLP is deployed without email security visibility?
A: DLP becomes a content filter with weak context.
Q: Why do compromised email accounts increase data exfiltration risk?
A: Because a legitimate mailbox already carries trust.
Q: How do organisations know if email security is actually working?
A: Look for fewer fraudulent requests reaching approval stages, faster triage of suspicious mail, and reduced analyst time spent on low-value noise.
Practitioner guidance
- Map lateral email abuse scenarios to identity controls Document how compromised mailboxes, internal phishing, and misdirected attachments pass through your current identity and email stack.
- Correlate DLP with mailbox behaviour and access context Join DLP events to sign-in anomalies, mailbox forwarding changes, unusual attachment patterns, and impossible travel signals.
- Shorten investigation paths across email and endpoint telemetry Build a single triage workflow for mail flow, endpoint evidence, and cloud file access so analysts can confirm scope in one case.
What's in the full article
Proofpoint's full article covers the operational detail this post intentionally leaves for the source:
- How the regional financial institution evaluated Microsoft Purview DLP gaps against email, endpoint, and cloud visibility needs
- The investigation and remediation workflow changes that improved SOC efficiency after replacing Mimecast
- The specific post-delivery detection capabilities used to surface lateral phishing and compromised account activity
- The DLP use cases, including screen capture monitoring, that were not fully covered by the existing stack
👉 Read Proofpoint's analysis of Microsoft DLP visibility gaps and email risk →
Email security visibility gaps: what they mean for DLP teams?
Explore further
14/07/2026 4:35 pm
Visibility, not policy volume, is the decisive weakness in email-driven data loss. The article shows that the organisation already had DLP controls, but still lacked enough context to understand lateral phishing and internal exfiltration. That is the more important lesson for regulated environments: policy coverage is not the same as operational visibility. When the detection stack cannot correlate identity, message flow, and data movement, the control fails where attackers actually operate.
A question worth separating out:
Q: Who is accountable when DLP fails to stop sensitive data leakage?
A: Accountability usually sits across security operations, endpoint management, identity governance, and the business owner of the data. If policy coverage depends on endpoints, identity, and exceptions all being aligned, no single team can claim ownership alone. Mature programmes assign control ownership by data path, not just by tool administration.
👉 Read our full editorial: Email security visibility gaps are undermining DLP programmes
