Custom-domain email for AI agents. A hosted email API on your own domain — one provider sign-in, no token to paste, and an inbox your agent can actually call.
deliveredinbound support@yourdomain.com 38 msinboxspam score 0.4sentoutbound welcome@yourdomain.com → Resendloggedevent webhook deliveredA preview of the activity feed in your dashboard
Where a domain stands
“Not connected” is not the same as “switched off”, and neither is the same as “we could not check”. Those three send you to three different places, so they look different here. Hover a state to read what it means.
How it works
Three steps, and all of them happen in the browser. There is no DNS record to hand-edit, no token to paste, and nothing to deploy on your side.
Sign in to your provider over OAuth — Cloudflare is the first one supported, and more are on the way. We never store an API token, and the authorization expires on its own; no long-lived credential of yours sits in our database.
Pick the domain your provider can route. DNS records are detected automatically; you approve the routing rules and the domain flips to active in under a minute.
Use the dashboard for human workflows, or call the REST API from your service code. Inbound mail lands in your domain's mailbox, the route table decides which addresses it accepts, and outbound is dispatched to the provider you picked for that domain.
How your mail moves
Inbound mail is captured by your provider's email routing and handed to Flowmails, where it lands in the mailbox for that domain. Outbound leaves through the channel you picked for that domain. Everything in between — inbox, outbox, route tables, events — is reachable from your code.
One letter, start to finish: your provider’s routing, the platform, the inbox — and back out through the channel you picked for this domain.
Why teams pick Flowmails
For AI agents
Three ways in, one mailbox behind them: point an MCP client at the hosted server, install the skill for a coding agent, or call the REST API — or the CLI — from your own service. Whichever one your agent already speaks, it lands in the same inbox on your own domain, under a key you can revoke.
Point a support agent, a research agent or a workflow runtime at one URL. Every call is checked against the credential's scopes, and there is no skill to install — MCP is a protocol, not a directory.
https://sdk.flowmails.net/mcpClaude Code, Cursor and Copilot install the skill from their own directory. One command, and every session starts from the same contract instead of whatever the model remembers.
npx skills add wms-why/flowmails-sdk-plugin@flowmails-sdkAnything that can make an HTTPS request is an agent here: send, wait for a reply, read it, search the mailbox, create an address. A backend needs no filesystem and no terminal.
npm install @flowmails/flowmails-sdkWhichever one your agent speaks, the first step is the same: sign in, pick a domain, mint a key. The key is bound to one domain and revoked in one click, so the worst case is one mailbox rather than an SMTP password. Every send lands in your outbox, and inbound mail is queryable through the API — so an agent can confirm a message landed instead of polling for it.
Try the API
Three copy-paste examples for the runtimes you actually use — pick one, paste it, ship. Every example targets the same wire endpoint, with the inbox and outbox landing in Flowmails' storage, scoped to your domain.
Plain curl against the REST endpoint — no SDK, no runtime. Send + receive with the simplest possible wire format.
Read the exampleSync or async — requests for blocking call sites, httpx for asyncio. Webhooks land in a FastAPI handler.
Read the exampleZero-deps fetch works in Node 18+, Workers, Bun, Deno. The official SDK adds typed errors and retry policy on top.
Read the exampleWhat you get
You sign in to your provider over OAuth and approve the routing rules in the same flow. That authorization is used only to finish the setup: it expires on its own, and we never keep a long-lived credential for your account.
$ flowmails connect
✅ Connected provider: cloudflare (OAuth grant, 24h)
domains available: 3Inbound mail is routed by your provider to a dedicated address for your domain and lands in your inbox. Outbound goes through Cloudflare Email Sending or Resend — you choose per domain — and there is no SMTP relay to operate.
$ curl -X POST https://sdk.flowmails.net/api/v1/messages \
-H "Authorization: Bearer fm_…" \
-d '{"to":"hi@yourdomain.com","subject":"hi"}'
{ "id": "8421", "status": "sent",
"messageId": "<abc123@yourdomain.com>",
"recipients": [ { "to": "hi@yourdomain.com", "status": "sent" } ] }Send over HTTPS with a key scoped to a single domain, and read what arrived through the same API. Inbox, outbox, route tables and the event log are all reachable from code, so a verification flow can wait for its mail instead of polling for it.
$ curl https://sdk.flowmails.net/api/v1/messages \
-H "Authorization: Bearer fm_…"
from_email subject
no-reply@stripe.com Order #8421 confirmedClaude Code, Cursor and Copilot install the flowmails-sdk skill and get the exact send, read and wait contract, the error hierarchy and the retry policy in every session. A hosted MCP server and a flowmails CLI ship alongside — a support agent, a research agent or your own service calls the same ten tools. Either way it gets a typed contract instead of invented method signatures, and a key scoped to one domain instead of SMTP credentials.
$ npx skills add wms-why/flowmails-sdk-plugin@flowmails-sdk
✔ installed: flowmails-sdk
→ fm.send(SendOptions) → SendResultAI draft and reply is in preview: model-backed drafting and summarization. Your prompt templates and the messages used as context stay with your domain's data, and you choose the model provider.
{ "model": "flowmails-draft",
"scope": "domain:yourdomain.com",
"prompt": "draft reply to support ticket #8421",
"context": "your own messages only" }Who it's for
An agent does the sending and the reading; the domain, the key and the bill stay with a person. Flowmails is for both — any agent that speaks MCP or plain HTTPS, and the teams who stay accountable for what leaves that domain.
Give any AI agent an API-keyed mailbox on your own domain — SDK, skill, a hosted MCP server and a CLI. Claude Code, Cursor and Copilot install the skill; anything that speaks MCP needs nothing else.
Read the agent pageRun a custom-domain email API from one connection. Send transactional mail from `hello@yourdomain.com` without ever touching an SMTP relay.
Read the pageRun an email API for support@, billing@, and abuse@, then read those mailboxes from your own backend.
Read the pageManage an email API for every client from one dashboard. Per-domain API keys, and a data boundary you can show in a review.
Read the pageWhen the requirement is 'email data stays in one place, with a documented boundary', a single-provider email API is the answer — not a marketing claim.
Read the pageSend order confirmations, password resets, and receipts from your custom domain over a REST API — no SMTP relay, no separate SaaS.
Read the pageIf your domain provider supports email routing, your domain works here. Connect it in the browser, pick an outbound channel per domain, and the first mailbox is live in about a minute.
Flowmails now integrates Rspamd, the high-performance open-source spam, phishing, and malware classifier, as the default scanner for every inbound message. The moment your provider's email routing hands a message over, Rspamd scores it against its rulesets: reject-classified mail is quarantined into a dedicated Junk tab and never reaches the live inbox, while borderline messages stay in Inbox with the verdict and the rules that fired surfaced in the reading pane.
Scoring happens right after the message is accepted, so Inbox latency is unchanged. If Rspamd is unreachable the email stays delivered — the system fails open rather than drop a real message because the scanner hiccupped.
{
"is_skipped": false,
"score": 24.4,
"required_score": 15.0,
"action": "reject",
"thresholds": { "reject": 15, "add header": 6, "greylist": 4 },
"symbols": {
"RBL_SPAMHAUS": { "score": 8.5 },
"URIBL_BLACK": { "score": 6.0 },
"MISSING_TO": { "score": 2.0 },
"MIME_HTML_ONLY": { "score": 1.0 }
}
}FAQ
From the journal
What the OAuth grant actually gives Flowmails, when it expires, and why the platform keeps no long-lived credential for your account.
ReadHow to hand an AI agent a mailbox it can call on your own domain: a contract it cannot misremember (the skill), a key it cannot overspend, and an inbox it can verify — without inventing the API.
ReadA suspended HTTP request dies on the edge long before the verification mail arrives. The wait is a row instead of an open connection: the platform answers immediately, the agent polls, and the answer survives the disconnect.
ReadCloudflare Email Routing is the world's best front door for inbound mail. It isn't a database, an inbox UI, a REST API, or a send path. Here's what you add — and why the answer is one email platform, not another SaaS.
ReadShip it on your domain
Custom-domain email on your own domain, live in about a minute — a hosted email API, one provider sign-in, no token to paste.