MultiMail provisions domains with SPF, DKIM, and DMARC alignment and adds signed identity metadata so every agent-sent email is both deliverable and provable.
Standard email authentication protocols — SPF, DKIM, DMARC, ARC — were designed for servers, not agents. They answer 'did this domain send this message?' but not 'which agent sent it, under whose authorization, and with what oversight level?' Teams building production AI agents hit this gap quickly: deliverability requires proper DNS alignment, but compliance under frameworks like the EU AI Act also requires provenance — knowing exactly which model instance generated an email and whether a human approved it. Bolting identity tracking onto standard authentication after the fact produces fragile, unauditable systems.
MultiMail handles both layers together. Domain provisioning generates DKIM keypairs, publishes SPF and DMARC records, and configures ARC sealing automatically. On top of that, every outbound message carries a cryptographically signed X-MultiMail-Identity header — an ECDSA P-256 claim that records the operator and mailbox identity, the oversight mode, the agent's capabilities, and the AI-generated flag. Recipients — and your own audit logs — can verify both the domain authentication chain and the agent provenance chain independently. This means standard spam filters see a properly authenticated sender while your compliance tooling sees a fully attributable agent action.
Call the domain configuration endpoint with your domain. MultiMail generates a DKIM keypair (RSA-2048 or Ed25519), returns the DNS records you need to publish, and sets the selector. You keep ownership of your domain; MultiMail signs on your behalf using the provisioned key.
Publish the TXT records for SPF (v=spf1 include:send.multimail.dev ~all), DKIM selector, and DMARC policy. MultiMail polls for propagation and runs an alignment check — SPF envelope-from, DKIM d= tag, and From header domain must all match for DMARC to pass. Misalignment is reported before you send a single message.
When your agent sends via POST /v1/mailboxes/{mailbox_id}/send (or replies via /reply/{email_id}), MultiMail appends a signed X-MultiMail-Identity header — an ECDSA P-256 signed claim covering the operator and mailbox identity, the oversight mode active at send time, the agent's capabilities, and the AI-generated flag. This identity claim is signed by MultiMail's own signing key (verifiable at /.well-known/multimail-signing-key) and is separate from the DKIM key on your domain — domain authentication and agent provenance are two independent layers.
Every outbound message leaves MultiMail with DKIM signature, SPF alignment, DMARC policy in effect, ARC sealing for forwarded messages, and the agent identity header. Your audit log records the full authentication state for every send event.
Pick your platform, copy the prompt, and paste it to your AI agent — it sets up MultiMail and builds the whole flow. Nothing to fill in.
MultiMail generates correct SPF, DKIM, and DMARC record values for your domain and verifies alignment before your agent sends a single message. Misconfigured authentication is the most common cause of AI-sent email landing in spam.
The signed X-MultiMail-Identity header records the operator and mailbox that sent each message, under which oversight mode, with which capabilities, and that it was AI-generated. This is separate from DKIM — domain authentication proves the sender, identity signing proves the agent.
The EU AI Act requires disclosure and traceability for AI-generated content. MultiMail's identity headers and audit log provide the artifact trail auditors need: operator and mailbox identity, oversight level, and the AI-generated flag on every message.
Authenticated Received Chain (ARC) preserves the authentication state when messages are forwarded through mailing lists or other intermediaries. MultiMail seals ARC headers automatically so your agent's email survives forwarding without losing DMARC pass status.
Every domain verification and send event is written to the MultiMail audit log, retrievable via GET /v1/audit-log. You can reconstruct exactly what was sent, when, from which mailbox, and under which oversight mode.
Email infrastructure built for AI agents. Verifiable identity, graduated oversight, and a hosted MCP server. Formally verified in Lean 4.