emdash-plugin-brevo: Brevo transactional email plugin (+ sandboxed plugin email detection bug)

[marcusbellamyshaw-cell]

emdash-plugin-brevo — Brevo transactional email for EmDash + a couple of things the team should know

Built a Brevo transactional email plugin for EmDash while setting up user invites and magic links on my own site (https://everybittexas.com). Sharing it in case it's useful, and also flagging a couple of rough edges I hit along the way that might be worth addressing in core.

Repo: https://github.com/marcusbellamyshaw-cell/emdash-plugin-brevo

What it does

Implements the email:deliver exclusive hook via Brevo's HTTP API. No Node.js dependencies, runs natively on Cloudflare Workers. Config (API key, sender name, sender address) is managed through the EmDash admin UI — no redeploy needed to rotate keys.

• Retry with exponential backoff on transient 5xx errors
• Skips retry on 4xx — auth errors and bad sender config won't self-heal
• Test send form built into the plugin admin page
• Accepts any Brevo API key format (xkeysib- and xsmtpsib- both work)

Install

npm install emdash-plugin-brevo

import { brevoPlugin } from "emdash-plugin-brevo";

emdash({
  sandboxed: [brevoPlugin()],
  sandboxRunner: sandbox(),
})

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Two things worth flagging for the core team

1. Settings > Email Settings doesn't detect sandboxed email providers

When an email provider plugin is registered via sandboxed:, the Email Settings page still shows "No email provider configured" even though email delivery is working correctly. The provider detection appears to only check non-sandboxed plugins.

The "Send Test Email" button on that page also fails for the same reason — it checks emdash.email.isAvailable() before attempting delivery, which returns false when the transport is sandboxed. So there's no way to test delivery from that page even when everything is working. The plugin's own admin page has a test send form as a workaround.

2. The Brevo API key validator was hardcoded to xkeysib-

This is specific to this plugin rather than core, but worth noting: the original version had a validator rejecting any key that didn't start with xkeysib-. Brevo actually issues SMTP keys starting with xsmtpsib- and those work fine with the HTTP API too. The validator has been removed in the current version.

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Happy to take PRs. If anyone wants to add reply-to support, attachments, or CC/BCC, the send logic is all in one place now so it should be straightforward.