Agent inbox
An agent inbox is an email address owned by an AI agent rather than a person, carrying its own thread history, its own permission grant, and a console where a human can hold outbound mail for review.
An agent inbox is not a mailbox with an API bolted to the side. The distinction is ownership. The address, the thread history, the credential and the audit trail all belong to the agent, and none of them are borrowed from a person who also uses that mailbox to talk to their accountant.
Three properties, and an implementation needs all three
Its own address. A live inbox is issued on agents.emailforagents.ai with a local
part you choose, subject to a reserved-name list that rejects postmaster, abuse
and similar with HTTP 422 reserved_address. Mail addressed there routes to that
inbox and nowhere else. Nothing arrives because a human forwarded it.
Its own credential. Access is granted per inbox, not per workspace. A REST key
names the project, the inbox IDs and the scope strings it carries; a remote MCP
connection names the project, the inboxes the human ticked on a consent screen, and
one of three presets. A single-purpose assistant can therefore hold inboxes:read,
threads:read, messages:read and nothing else, against one mailbox.
Its own review path. Whether a send transmits or waits is a property of the inbox
and the credential together, not of the agent’s own judgment. An inbox policy set to
approval_mode: "always" holds every message regardless of how powerful the
credential is, and a credential holding drafts:submit without messages:send is
held even on an inbox configured for direct sending. Both come back as HTTP 202 with
"result": "approval_required", which is the detail that catches integrations: a 202
does not mean the mail is in flight. Branch on result, never on the status code.
What it is not: a mailbox a bot logs into
The common alternative is connecting an agent to a human’s existing account through OAuth. That is a different thing wearing the same words, and the differences are structural rather than cosmetic. The agent acts as that person, so every message it sends is from them and every message they receive is visible to it. Narrowing what the agent may do means narrowing what the human may do. Revoking the agent revokes a token the human also depends on. The comparison is worked through in full in an agent inbox versus a connected Gmail account.
An agent inbox inverts each of those. The agent’s identity is its own, so a recipient who replies is replying to the agent. Its permissions are its own, so they can be cut to read-only without affecting anybody. And a revoked grant stops the agent while leaving every human mailbox untouched.
What one costs to run
Usage is counted in email units. One unit is one message received, or one recipient sent to, so a reply addressed to three people costs three. The free allowance is one complimentary live inbox and 100 email units a month per verified owner identity, claimed by that identity’s first eligible workspace. Creating a second workspace does not renew it.
Receiving is the half people forget to budget for. A support inbox that takes 40 messages and answers each of them once has spent 80 units, not 40. When the allowance runs out sending stops, and mail already received stays readable. The full breakdown is on the pricing page.
What an agent inbox does not give you
It does not give you deliverability. A message the provider accepts is a message the provider has taken responsibility for, which is a weaker statement than most dashboards imply, and no email system can report whether a recipient’s server filed the message in a spam folder.
It does not give you a custom domain today. Custom domains require a paid plan, and
paid plans are not purchasable yet, so live mail is sent and received on
agents.emailforagents.ai.
And it does not give you a test environment by accident. A test inbox is a separate thing on a non-routable address, created in a project whose environment is fixed at creation and cannot be promoted. If you want to exercise the loop before a recipient is involved, that is the object you want, and the product overview covers how the two environments sit side by side.