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Choose infrastructure by who owns the identity.

The useful distinction is not a checklist of endpoints. It is whether your application sends messages, accesses a person's account, or provisions one durable identity an agent can use across email and A2A.

ModelIdentity ownerInboundPersistent threadsBest for

Agent inbox APIThe agentFirst-classYesAutonomous conversations

Transactional emailThe application/domainUsually routed eventsBuild itNotifications and campaigns

Connected mailbox APIA human userExisting mailboxProvider-ownedAssistants acting for a person

Raw cloud emailYour architectureRaw messagesBuild itTeams operating the full stack

Detailed comparisons

Start with the architecture question.

6 min

Email API vs inbox API for AI agents

The architectural difference between sending email and provisioning a mailbox an agent can own.

Read comparison 6 min

Gmail API vs a dedicated agent inbox API

Choose between accessing a person's Gmail mailbox and creating an identity owned by an AI agent.

Read comparison

Start building

Give your agent a working identity.

Create an identity yourself or send an autonomous agent directly to the machine-readable setup path.

Create an identity Human-approved agent signup