Can I call the API from a Node / Python / Bun app, or only edge runtimes?

Any runtime that can speak HTTPS can call the send endpoint. The official `@flowmails/flowmails-sdk` wraps the REST call for Node, Bun, and Deno; edge-runtime calls go through the same SDK or the raw REST endpoint.

How does the SDK compare to Resend / SendGrid SDKs?

Same shape: `fm.send({ from, to, subject, html, text, attachments })` returns a `{ id, status }` object. The difference is that Flowmails sits on top of the provider you already chose, so you are not forced onto a single vendor's billing.

What happens if my provider has an outage?

Provider status is published by the provider — cloudflarestatus.com for Cloudflare, status.resend.com for Resend. Flowmails surfaces accepted / rejected / failed events to your dashboard and to the sent row, so your application can react. There is no automatic retry layer in the base product — pair Flowmails with a small in-app retry queue if your SLA requires it.

Custom domain · Your providersFlowmails

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For Transactional email API

One API · any provider

Transactional email API — POST to one endpoint, no SMTP relay

Serverless runtimes can't talk to a traditional SMTP relay without a third-party bridge. Most teams bolt on SendGrid or Resend to fill that gap, which means a separate billing relationship, a separate dashboard, and a per-email fee. Flowmails removes the bolt-on: you POST to one endpoint (or use the Flowmails SDK from any runtime), and the message goes out through Cloudflare Email Sending — via a thin sender worker we deploy in your own account — or through Resend, whichever you picked for that domain. There is no SMTP relay, no per-email markup from Flowmails, and no shared sending IP from a SaaS. Transactional senders typically ship the first email in under an hour: connect the provider, verify the domain, mint an API key, hit the SDK.

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What hurts today

The transactional email api pain points

Serverless runtimes can't natively SMTP — most teams bolt on SendGrid / Resend

Per-email pricing compounds fast at scale (10K+ transactional emails / month)

Hosted ESPs add a separate dashboard, separate billing, and a shared sending IP

How Flowmails answers

What you get instead

A single `POST` to the send endpoint from any HTTPS-capable runtime

Outbound goes through Cloudflare Email Sending or Resend — no SMTP relay, no per-email markup from us

Your domain sends from its own provider account, so DKIM / SPF / DMARC align automatically

FAQ

Common questions from transactional email api

Other personas

All Flowmails for pages

For AI agents For Indie developers For SaaS support teams For Agencies and studios For Privacy-sensitive products