How AI agents get a real inbox, pay per call instead of by the seat, and send and receive email without a human in the loop. Guides, comparisons, and deep dives from the team building DimeBox.
There's no password reset for an inbox — lose the read token and you lose read access permanently, even though the inbox and its address keep sending and receiving mail.
No account, no login, and DimeBox never records which wallet paid to create an inbox — ownership here means holding a token, not holding a login.
Names like admin, support, billing, and paypal are permanently blocked — claiming one always fails, no matter who asks or what they pay.
Set a webhook_url when you provision an inbox and get a signed POST the moment new mail arrives, instead of polling for it.
An inbox keeps only its newest messages — once you hit the cap, the oldest one drops to make room for the new one.
No IMAP, no webmail, no folders — an agent inbox is a flat list of messages on purpose, not a cut corner.
Pick your own inbox slug instead of a random one — a one-time $1.00 payment that checks availability before you pay, not after.
The read token handed back when an inbox is created is the only credential that can read it — there's no password, no account recovery, and no second copy.
One POST request is all it takes to get an AI agent a working email address — no signup form, no account, no API key.
An agent inbox is a real email address an AI agent can draft from, send from, and receive into, provisioned with one HTTP call instead of a signup form.
Replay protection, facilitator trust, and what happens when a call fails partway — a working threat model for pay-per-call APIs, not a yes/no answer.
Testing x402 payments against real USDC costs real money on every mistake. Base Sepolia runs the same protocol with test tokens that don't.
A signed payment isn't money moved yet. A facilitator verifies it and submits it on-chain — a job deliberately kept separate from the API server.
EIP-3009 lets an agent sign a USDC payment without holding a separate gas token at all — here's what the signature actually contains.
x402's default payment method pays the exact quoted amount for the exact request that triggered it — no running balance, no invoice, no tip jar.
Why DimeBox prices every call in USDC and settles on Base specifically, not any stablecoin on any chain.
What's actually inside a 402 response, what a client has to build in reply, and what a server checks before it runs the route — walked through stage by stage.
API keys answer who's calling. x402 answers whether this specific call got paid for — a narrower question that fits an autonomous caller better.
HTTP reserved a status code for payment in 1997. It took cheap stablecoin settlement and machine callers with no use for a checkout page to finally use it.
x402 turns the long-unused HTTP 402 status code into a working payment handshake: call an endpoint, get asked to pay, sign a payment, get your response.