Scope email to the task
A signup code, a vendor thread, a delivered file, a receipt: zero onboarding, a fixed price, scheduled deletion, and no spam surface attached to your name.
COMPARISON
Machine Inbox vs AgentMail.
Both give software agents an email address over an API. AgentMail is a subscription email platform for persistent agent identities with outbound sending. Its agent self-onboarding confirms a human email with a one-time code before an inbox is unrestricted. Machine Inbox sells one task-scoped inbox per payment, with no account, no human in the loop, and no outbound conversations. The details below reflect published information as of August 2026. Check both vendors for current terms.
SIDE BY SIDE
Different shapes for different jobs.
| Dimension | Machine Inbox | AgentMail |
|---|---|---|
| Pricing model | Per inbox: $0.05 (1 hour, x402; $0.50 by card), $2.00 (7 days), $5.00 (30 days) | Monthly subscription tiers ($20, $200, enterprise), renewing whether or not mail arrives |
| Account required | No: the payment is the onboarding, with no human in the loop | Yes for standard tiers; agent self-onboarding still confirms a human email by OTP before the inbox is unrestricted |
| Outbound email | Replies to authenticated inbound senders only, so there is no spam surface | Open outbound sending: a spam and reputation surface you must police |
| Custom domains | No: inboxes live on the service domain | On paid tiers, after DNS setup you maintain |
| Webhooks / push | Signed per-inbox webhooks plus a long-poll wait endpoint | Webhooks and WebSocket into infrastructure you operate |
| Verification-code extraction | Dedicated endpoint included | Build it yourself from message APIs |
| Data retention | Deleted at expiry, or earlier on request | Mail accumulates for as long as the subscription runs |
| Payment rails | Stripe MPP and x402, advertised in one 402 | Card billing; x402 and MPP integrations |
GUIDANCE
Why buy the inbox per task.
Keep your domain out of it
Experiments, burst tasks, and one-off signups run on disposable Machine Inbox addresses instead of touching your primary domain's reputation.
Pay only when mail matters
Each inbox is one payment with a known end date. Nothing renews, nothing bills while idle, and there is no account to cancel.