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Use cases → Email operations

Apply encryption to outbound email by policy

Scan and encrypt outgoing messages when they match defined criteria, using a service account operating with domain-wide delegation.

Who it is forIT and security teams automating compliance for sensitive outbound communications.
APIsGmail API
Typical scopesgmail.modify, gmail.send

The problem

Sensitive emails are often sent unencrypted because users forget or do not know policy requirements. Manual enforcement is unreliable and after-the-fact intervention is too late.

How it works

  1. Use a service account with domain-wide delegation to monitor outbound messages via Gmail API.
  2. Define rules to identify messages requiring encryption based on content, recipient, or labels.
  3. Intercept and apply encryption before release, modifying the message or re-routing as needed.
  4. Send the encrypted message on behalf of the user, ensuring traceability and delivery.

What changes

Sensitive messages are encrypted automatically when required, with no user decision or delay, and compliance is logged centrally.

The trap in this one. If the service account attempts to modify or re-send a message that has already left the outbox (due to rapid delivery), the Gmail API will not retroactively encrypt or recall the message—no error is thrown, but the email leaves unencrypted. This race is common under high send volumes or when Gmail's delivery pipeline is fast, so always intercept at draft or pre-send stage, not after.

Watch it explained

“Google Workspace CSE with Thales CCKM demo v3” — shaun chen on YouTube. Third-party video, included because it covers this ground well. We are not affiliated with the channel.

Questions people ask

Can encryption be applied to all outgoing mail?

Technically yes, but this increases user friction and can break workflows with recipients who are not prepared for encrypted messages. Apply policy-based rules instead.

What encryption methods are supported?

Most implementations use S/MIME or PGP; the service must have access to the relevant keys and be able to insert encrypted payloads before sending.

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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