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Use cases → Email operations

Flag emails with policy-enforced keyword scanning

Automatically scan and flag emails containing sensitive or policy-restricted keywords using a delegated service account, enforcing compliance without relying on user vigilance.

Who it is forCompliance or security teams tasked with monitoring outbound and inbound communications.
APIsGmail API
Typical scopesgmail.readonly, gmail.modify

The problem

Users routinely overlook or bypass manual keyword guidelines, leading to accidental data leakage or policy violations. Reliance on end-user judgement is inconsistent and audits after the fact are slow and incomplete.

How it works

  1. Delegate a service account with domain-wide authority to access user mailboxes.
  2. Regularly poll for new messages using the Gmail API, filtering by time or message ID.
  3. Scan message bodies and attachments for policy keywords.
  4. Label, quarantine, or notify based on detected matches, using the Gmail API to apply labels or move messages.
  5. Log all flagged events for downstream review.

What changes

Emails violating policy are flagged or handled automatically, and compliance teams get immediate visibility into incidents.

The trap in this one. Gmail API's history tracking is eventually consistent and subject to gaps if messages are quickly deleted or modified. If the polling interval is too long, messages can be missed entirely—especially if users delete or archive them before the scanner sees them. The API's historyId can also roll over, which breaks incremental scans and requires a full resync.

Watch it explained

“How To Allow Service Account Key Creation in Google Cloud Platform” — TV2VN on YouTube. Third-party video, included because it covers this ground well. We are not affiliated with the channel.

Questions people ask

Does this work for both inbound and outbound mail?

Yes, scanning can be applied to any message in the user's mailbox, but ensure the service account has the necessary scopes for both Sent and Inbox.

Can users see that their emails have been flagged?

If you apply a label or move the message, users will see the flag. For silent monitoring, log events server-side only.

Want this built?

This is a pattern we run in production. We will set up the delegation and build this on top of it — $500 per hour, most of it working the same day.

Talk to us Or read the setup guide

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