SendEmail.send returns a wrong type in development environment

[ranile]

What versions & operating system are you using?

  System:
    OS: macOS 26.3.1
    CPU: (12) arm64 Apple M3 Pro
    Memory: 90.88 MB / 18.00 GB
    Shell: 4.5.0 - /opt/homebrew/bin/fish
  Binaries:
    Node: 24.4.1 - /Users/elina/.local/state/fnm_multishells/45976_1776250154175/bin/node
    Yarn: 1.22.22 - /Users/elina/.local/state/fnm_multishells/45976_1776250154175/bin/yarn
    npm: 11.4.2 - /Users/elina/.local/state/fnm_multishells/45976_1776250154175/bin/npm
    pnpm: 10.28.1 - /Users/elina/.local/state/fnm_multishells/45976_1776250154175/bin/pnpm
    Deno: 2.6.10 - /opt/homebrew/bin/deno
  npmPackages:
    @cloudflare/vitest-pool-workers: ^0.12.4 => 0.12.21 
    wrangler: ^4.83.0 => 4.83.0 

Please provide a link to a minimal reproduction

https://github.com/ranile/cf-worker-email-send-wrong-type-bug

Describe the Bug

// ...
const result = await env.EMAIL.send(message);
console.log('email result', result); // logs undefined

Worker configuration has SendEmail.send typed as send(message: EmailMessage): Promise<EmailSendResult>;, however the real type is undefined

https://github.com/ranile/cf-worker-email-send-wrong-type-bug/blob/583d43210b0bd6577d10fab04dd17a31566cad87/worker-configuration.d.ts#L10788

Steps to reproduce:

1. Clone repository
2. pnpm install
3. pnpm run dev
4. curl localhost:8787

Please provide any relevant error logs

$ curl localhost:8787
undefined

[wrangler:info] send_email binding called with the following message:
  /var/folders/lw/m_yrcjv15f5bwgl1r25dr03w0000gn/T/miniflare-53ea533ca8803414f3caed41a5c41923/files/email/db254f42-c6ec-4c8c-b861-f5006b6254f7.eml
email result undefined

[dario-piotrowicz]

Thanks for the issue @ranile 🙂

A fix for it it's already on its way 😄 (#13577)