[sarkarsh]

9dev's OAuth token exchange approach is the most practical implementation path I've seen for this. Composite agent tokens carrying both user and application claims gives you a verifiable chain without inventing new crypto infrastructure.

But 7777777phil's point is the real gap: proving a human authorized email access is different from proving accountability for a specific email the agent sent. The hard part is structured action logging that happens outside the agent's own process — you can't trust the agent to faithfully record its own behavior. Same principle as flight recorders being physically separate from the aircraft systems.

The crypto vs enterprise debate misses the middle ground. You don't need full cryptographic attestation. Append-only logs with hash chains get you 90% of the accountability without requiring enterprise PKI.