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Getting started File 004

Postboi compared

How Postboi stacks up against Resend, SendGrid, Postmark and nodemailer. Postboi is an email provider in its own right, and using someone else's is optional.

If you’re choosing between Postboi and another email service, start here: Postboi is an email provider. We run the sending infrastructure, same as Resend, Postmark or SendGrid do, and postboi on npm is the SDK for it. A POSTBOI_TOKEN is all you need. You don’t need an account anywhere else.

On top of that, the same mail() call can send through another provider if you’d like it to, and the same API sends SMS, WhatsApp, push and chat as well. Both are extras.

Is Postboi a wrapper around other providers?

No. We support 40-odd other providers, which makes it easy to assume Postboi sits on top of them. It works the other way round:

  1. Postboi is an email service. The Postboi provider handles sending, custom domains, lists and broadcasts, contacts, double opt-in, suppressions, a message log, delivery webhooks, scheduling, hosted forms, receiving, email testing and a dashboard.
  2. postboi is its SDK. mail() and friends, with one error type, in any JS framework.
  3. You can point the SDK elsewhere. Send through another provider instead, or keep our log and dashboard while relaying delivery through your own Resend, Postmark or SES account.

So “Postboi or Resend?” compares two email providers.

Postboi vs Resend

Postboi Resend
Email provider with managed sending ✅ ✅
TypeScript SDK ✅ mail() ✅ resend.emails.send()
Works without any other provider account ✅ ✅
First send with no DNS and no card ✅ from you@send.postboi.email Needs a verified domain for real recipients
Custom domains, webhooks, scheduling ✅ ✅
Lists, broadcasts, contacts ✅ ✅
Switch provider without rewriting your code ✅ one line of config ❌ your code calls Resend’s API
SMS, WhatsApp, push and chat in the same API ✅ ❌ email only
Turn FormData into an HTML email ✅ ❌
Hosted form endpoints (no backend) ✅ ❌
Local dev inbox, no code changes ✅ /__postboi ❌
An agent can set it up without you signing in ✅ postboi init --agent Needs an account and API key first
Ecosystem and track record Newer ✅ bigger, been around longer

This is Resend as we understand it in September 2026. Check resend.com for what it does today.

Pick Postboi if you want as little code as possible between your app and a sent email, if an AI agent is setting things up, if you’ll want SMS or push later, or if you’d like to be able to change provider without touching your code.

Pick Resend if you want its ecosystem, its React Email tooling (React Email works with Postboi too, since body takes any HTML) or its longer history in production.

Already using Resend? You can keep it. postboi/resend sends through your Resend account using Postboi’s API, and if you move to the Postboi provider later, you change provider: "resend" to provider: "postboi" and that’s it.

Postboi vs SendGrid, Postmark, Mailgun or SES

Same story as Resend. Each is an email provider with its own SDK, and code you write against that SDK only sends through them. Postboi is also an email provider, and its SDK can send through any of them too. So you can use Postboi instead of them, or keep one and stop your app depending on it directly.

Postboi vs nodemailer

nodemailer is a library. You still need an SMTP server or a provider behind it, and you don’t get a delivery log, suppressions or webhooks. Postboi is a provider and a library, so bunx postboi init replaces installing nodemailer, signing up somewhere and pasting in SMTP credentials. If you do want SMTP, Postboi supports that too (postboi/smtp).

Why it works well with AI agents

  • Setup is one command and nobody has to sign in. bunx postboi init --agent creates a project the agent can use straight away. You claim it with one click when you’re ready.
  • Every channel looks the same. mail({ to, subject, body }) writes the plain-text version for you, and sms(), push() and the rest take the same shape and fail the same way.
  • Errors have one shape. Whichever provider fails, you get a PostboiError, with a code when the provider gave one. On the Postboi provider that’s one of ours, like rate_limited or from_not_allowed. Other providers pass their own codes through.
  • Mistakes show up as type errors. postboi sync types from to the addresses your account can send from, and form names to the forms you have.
  • The docs are easy for a model to read. The package ships a skill (bunx postboi skill), every page is plain Markdown at /raw/<slug>, and the whole site is one file at /llms-full.txt.