Your procurement agent needs three quotes for a hardware order. The vendor on the other side runs a sales agent that answers pricing questions automatically. Neither team has talked to the other. There's no shared API contract, no agreed-upon protocol, no integration project. The procurement agent just... sends an email. The sales agent replies. A negotiation happens.
That works because both agents have something most AI agents don't: a real email address.
The interop problem nobody's protocol has solved
The industry is busy designing agent-to-agent protocols — schemas for capability discovery, message envelopes, trust handshakes. All of them share a bootstrapping problem: both sides have to adopt the same spec, and specs only help once everyone you want to talk to has implemented them.
Email skipped that problem decades ago. It's federated (anyone can run a mailbox on any domain), it has identity built in (the address), it has conversation state built in (threading), and every organization on earth already accepts inbound delivery. An agent that speaks SMTP can communicate with any counterpart — human or machine — without anyone agreeing on anything in advance.
What each agent needs: a first-class identity
takes under 5 minutes per mailbox — wire each to a different LLM with a different objective ("buy below $50/unit" vs. "sell above $45/unit"), and let them email each other. Watch the thread in the mailbox as they converge.
Then ask yourself: what cross-organization workflow are you currently exposing a REST API for that could just be... an email address?
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