Glossary
The words agent email is built out of
One sentence each, then the detail underneath. Every definition names the exact field, scope string or error code it describes.
How to read these
Each entry opens with a definition written to be quoted on its own, with no surrounding paragraph to lean on. Below it is the part a definition cannot carry: what the thing costs, where it is enforced, and the case where the obvious reading of the word is wrong.
Where a term names something the product does not do, the entry says so in the same breath. If you want the working code rather than the vocabulary, the quickstart is the shorter route, and the guides go deeper on every term here.
A
- Accepted versus delivered
- Accepted versus delivered is the difference between a provider taking responsibility for a message and a receiving server storing it, the first observable at send time and the second reported later, or never.
- Agent email address
- An agent email address is the mailbox identity an AI agent sends and receives from, issued on agents.emailforagents.ai for a live project and as a generated non-routable address for a test project.
- 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.
- Approval gate
- An approval gate is a policy layer that turns an agent's send into a pending request a named human must decide, returning a held result instead of a message ID until somebody approves the exact content reviewed.
C
- Connection grant
- A connection grant is the OAuth authorisation a human approves in a browser so an agent client may call MCP tools on named inboxes, expiring after 30 days and revocable without rotating any shared secret.
E
- Email unit
- An email unit is the usage unit for agent mail, counting one message received or one recipient sent to, so a single send addressed to three people consumes three units and test mail consumes none.
I
- Idempotency key
- An idempotency key is a caller-supplied string naming one intended message rather than one attempt at sending it, so a retried request replays the original response instead of producing a second email.
M
- MCP tool surface
- An MCP tool surface is the set of tools a connection is shown by tools/list, computed from that connection's scopes, so a capability the grant does not carry is never named to the model at all.
S
- Scoped grant
- A scoped grant is a credential limited to named projects, inboxes and permission scopes, whose effective authority is recomputed from current database state on every request instead of being trusted as a fixed claim set.
T
- Test inbox
- A test inbox is a mailbox on a generated, non-routable .mail.invalid address with a simulated transport, producing real events, approvals and error codes while being unable to reach any internet recipient.
Where the definitions come from
Every scope string, event name, error code and limit on these pages is read from the deployed implementation, not from a marketing brief. Where the current build declares something it does not yet emit, the entry says which is which.
The permission model is laid out in full on approvals and permissions, the REST surface on the email API page, and the MCP server on integrations.