Choose AgentMail when
Your agent is a durable product identity: it sends outreach, manages long-running correspondence, needs your own domain, and benefits from a searchable archive and webhook infrastructure.
COMPARISON
Machine Inbox vs AgentMail.
Both give software agents an email address over an API. The honest difference is shape: AgentMail is a subscription email platform for persistent agent identities with outbound sending; Machine Inbox sells one task-scoped inbox per payment, with no account and no outbound conversations. 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: $0.50 (1 hour), $2.00 (7 days), $5.00 (30 days) | Monthly tiers: free (3 inboxes), $20, $200, enterprise |
| Account required | No: the payment is the onboarding | Yes for standard tiers; a wallet-based x402 path exists |
| Outbound email | Replies to authenticated inbound senders only | Full outbound sending to arbitrary recipients |
| Custom domains | No: inboxes live on the service domain | Yes, on paid tiers |
| Webhooks / push | Long-poll wait endpoint | Webhooks and WebSocket |
| Verification-code extraction | Dedicated endpoint included | Build from message APIs |
| Data retention | Deleted at expiry, or earlier on request | Persistent archive while subscribed |
| Payment rails | Stripe MPP and x402, advertised in one 402 | Card billing; x402 and MPP integrations |
THE HONEST GUIDANCE
Pick by identity lifetime.
Choose Machine Inbox when
The email need is scoped to a task: a signup code, a vendor thread, a delivered file, a receipt. You want zero onboarding, a fixed price, automatic deletion, and no spam surface attached to your name.
Use both when
Your product identity lives on a platform mailbox while burst tasks buy disposable Machine Inbox addresses, keeping experiments and one-off signups off your primary domain's reputation.