Migrating from EmailJS

Frontmail was designed so that moving from EmailJS takes minutes: the browser SDK has the same function signatures, the REST API accepts the same fields, and the template syntax is compatible for simple templates.

Step by step

1. Create your organization and connect the service

Sign up at app.frontmail.dev and connect the same email provider you use in EmailJS (see Services). If you used a Gmail or Outlook service, reconnect it via OAuth; for SMTP or API providers, enter the same credentials.

2. Recreate your templates

Create a template for each EmailJS template. Copy subject, To, From, Reply-To and the content. Then click Detect parameters and set types and required flags – see template syntax below for differences.

3. Map the keys and IDs

EmailJS	Frontmail	Where to find it
Public Key (user_id)	Public key pk_…	Security → Public key
Private Key (accessToken)	Private key sk_… – server only	Security → Private keys (shown once)
Service ID	Service ID svc_…	Email services
Template ID	Template ID tpl_…	Templates
Domain allowlist	Allowed websites	Security → Allowed websites
reCAPTCHA	Cloudflare Turnstile with your own free widget	Keys in Security → Bot protection (Turnstile), per template Settings → Protection → Require CAPTCHA (Turnstile)

4. Change the import

import emailjs from '@emailjs/browser';
import emailjs from '@frontmail/emailjs-compat';

Your emailjs.init(), emailjs.send() and emailjs.sendForm() calls keep working – only the IDs and the key change. See EmailJS compatibility.

Don’t ship accessToken to the browser

Many EmailJS snippets pass the private key as accessToken in init() or in the send options. Remove it from browser code and use only the public key there. A Frontmail private key bypasses the origin allowlist and CAPTCHA and can read the message history of your whole organization (every contact form submission) – anyone can copy it from the page source. In a browser, @frontmail/emailjs-compat therefore rejects accessToken with status 400 (private_key_in_browser). Use the private key only on your server – the REST API with Authorization: Bearer sk_… or @frontmail/node. If a private key was ever part of a deployed page, rotate it in Security → Private keys.

Using the CDN script? Replace the EmailJS <script> with the compat build, which exposes the same emailjs global, so your calls stay unchanged:

<script
  src="https://cdn.jsdelivr.net/npm/@frontmail/emailjs-compat@0.1.0/dist/emailjs-compat.umd.js"
  integrity="sha384-RH+fuNzBqTKgxDJBHRmWfOn37fs33L+Or1ujDV7wThynx9FxD9uPptLu80LpCrEc"
  crossorigin="anonymous"></script>

Pin the exact version and keep the integrity attribute – see Pin the version for where to find the hash of newer releases.

Alternatively, load the native SDK (@frontmail/browser, same pinning) and rename emailjs. calls to frontmail. – the arguments are the same, but the promise resolves with status: 'queued' or 'held' instead of 200.

Calling the REST API directly? Change the host to https://api.frontmail.dev. The paths /api/v1.0/email/send and /api/v1.0/email/send-form and the body fields stay the same.

5. Turnstile instead of reCAPTCHA

If your templates used reCAPTCHA, remove the reCAPTCHA widget and add Turnstile. Just like with reCAPTCHA, you use keys from your own account: create a free Turnstile widget in Cloudflare, paste its keys into Security → Bot protection (Turnstile) and click Turn on CAPTCHA for all templates; new templates then require it by default. Put the widget with your site key into the form – see Turnstile. The g-recaptcha-response field is not used.

6. Test and switch

Send a test from the template editor, deploy, and watch History. Keep your EmailJS account until you’ve seen real traffic go through.

7. Optional: move to the native SDK

@frontmail/browser or a framework SDK gives you typed params, held status, getStatus() and typed errors.

Template syntax

Frontmail uses Handlebars; EmailJS uses a Mustache-like syntax. Common cases:

EmailJS	Frontmail	Notes
{{name}}	{{name}}	Same. Always HTML-escaped in Frontmail.
{{{html_content}}}	{{html_content}} with param type html	Triple braces don’t disable escaping in Frontmail; use the sanitized html type.
{{#if}}-style sections from Mustache {{#name}}…{{/name}}	{{#if name}}…{{/if}}	Use explicit Handlebars blocks.
Mustache inverted section {{^name}}…{{/name}}	{{#unless name}}…{{/unless}}
Lists via sections	{{#each items}}…{{/each}} with a list param	Define itemFields for validation.
–	{{formatDate}}, {{formatMoney}}, {{eq}}…	Extra helpers.

Default values set in EmailJS template fields map to the param’s default in Frontmail.

Comparison

A factual comparison of features relevant for migrating, as of September 2026. Pricing and limits of both services change over time – check the providers’ own pages before deciding.

	EmailJS	Frontmail
When monthly quota is used up	Requests are rejected until the next period or an upgrade	Messages are held and sent automatically when credits are added; optional overdraft and auto top-up
Prepaid credit packs with validity	Not offered	5k / 25k / 100k packs valid 3–12 months, on every plan
REST API rate limit	1 request per second	2–50 requests per second depending on plan, plus /v1/send-batch
Template language	Variables with simple sections	Handlebars with conditions, loops, helpers and typed, validated params
CAPTCHA	reCAPTCHA v2	Cloudflare Turnstile, on for all templates in one click
Provider failover	Not offered	Fallback service per template, daily health checks
Delivery tracking	Not offered	Delivered / bounced / complained / opened / clicked via provider webhooks
SDK retries and idempotency	Not documented	Automatic retries with idempotency keys
Framework SDKs	Browser SDK, React Native SDK	Browser, React, React Native, Vue, Svelte, Node, EmailJS-compatible

If you spot an outdated statement here, please tell us at support@frontmail.dev and we’ll fix it.