fix(miniflare): return EmailSendResult from send_email binding's send() by connyay · Pull Request #13577 · cloudflare/workers-sdk

connyay · 2026-04-17T03:08:35Z

The binding's send() resolved to undefined, diverging from production (and the public SendEmail type), which returns { messageId }. Workers that inspect the return value now see the same shape locally as deployed.

EmailMessage path: echo the parsed Message-ID with angle brackets stripped
MessageBuilder path: synthesize the id in the same <hex>@example.com form already used by the forward() path

Tests
- Tests included/updated
- Automated tests not possible - manual testing has been completed as follows:
- Additional testing not necessary because:
Public documentation
- Cloudflare docs PR(s):
- Documentation not necessary because: matching prod behavior

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The binding's `send()` resolved to `undefined`, diverging from production (and the public `SendEmail` type), which returns `{ messageId }`. Workers that inspect the return value now see the same shape locally as deployed. - EmailMessage path: echo the parsed Message-ID with angle brackets stripped - MessageBuilder path: synthesize the id in the same `<hex>@example.com` form already used by the forward() path

changeset-bot · 2026-04-17T03:08:41Z

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workers-devprod · 2026-04-17T03:08:57Z

Codeowners approval required for this PR:

✅ @cloudflare/wrangler

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connyay · 2026-04-17T03:10:17Z

I hit this trying to wire up email sending in workers-rs 👉 cloudflare/workers-rs#975

Co-authored-by: devin-ai-integration[bot] <158243242+devin-ai-integration[bot]@users.noreply.github.com>

pkg-pr-new · 2026-04-17T03:20:21Z

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commit: 2df9c5c

dario-piotrowicz

Looks good to me, thanks @connyay 🙏

workers-devprod

Codeowners reviews satisfied

cloudflare/workers-sdk#13577 landed

* feat(worker): add send_email binding support Adds a `SendEmail` binding and `EmailMessage` type so workers can dispatch email via the Cloudflare Email Sending service configured under `[[send_email]]` in wrangler.toml. Includes worker-sys bindings for `cloudflare:email`, a runnable example under `examples/send-email`, and integration tests. * feat(worker): add structured Email builder for send_email binding Extend the SendEmail binding to cover the public-beta builder overload in addition to the raw MIME path. Adds `Email`/`EmailBuilder`, `EmailAddress`, `EmailAttachment` (with `AttachmentContent::{Base64, Binary}`), and `EmailSendResult { message_id }`. `SendEmail::send` now takes `&Email`; the raw MIME path moves to `SendEmail::send_mime(&EmailMessage)`. * address pr comments * remove miniflare workaround cloudflare/workers-sdk#13577 landed * cleanup comments & example readme * use ts-gen for email * Auto-gen email bindings via ts-gen anonymous interface synthesis Drops the hand-written Email/EmailBuilder/EmailAddress/EmailAttachment types in worker/src/send_email.rs in favour of the auto-generated SendEmailBuilder, EmailAddress, EmailAttachment, etc. that ts-gen now synthesises from the d.ts. send_email.rs is reduced to the EnvBinding trait impl on the auto-gen SendEmail extern type and re-exports. types/email.d.ts renames the global EmailMessage interface to StructuredEmailMessage to keep it unambiguously distinct from the cloudflare:email-imported EmailMessage constructor class. The chompfile prepends a `use email::EmailMessage` to the generated file so the top-level send(message) signature resolves cross-module — removable once ts-gen handles same-file module imports natively. All 133 npm tests pass; both legacy raw-MIME and modern structured send paths work end-to-end. * add new_with_readable_stream test * Pull cross-module qualification + new builder ergonomics from ts-gen ts-gen learned three things since the last sync that simplify the email surface here: * Cross-module type references emit qualified Rust paths (`&email::EmailMessage` from a `Global` extern block referencing the `cloudflare:email` class). Drops the `chompfile.toml` postprocess that was prepending `use email::EmailMessage;` to the generated file. * Built-in `web_sys` defaults — `Headers`, `Event`, `ReadableStream`, etc. resolve to `::web_sys::*` automatically, so those `--external` flags are redundant. Only the project-specific `Env` and `ExecutionContext` mappings remain in the chompfile. * New dictionary builder shape: required fields go through the constructor, `build()` is infallible, literal discriminators collapse into the function name. Call sites update from `SendEmailBuilder::builder().from(x).build()?` to `SendEmailBuilder::builder(from, to, subject).build()` (or `::new(from, to, subject)` when no optionals are needed). `types/email.d.ts` collapses to a single `class EmailMessage` inside `declare module "cloudflare:email"`. The previous global-interface + module-class split (mirroring upstream `@cloudflare/workers-types`) was producing two distinct Rust types that both lowered to the same JS object, which forced an `unchecked_ref` at the `reply()` call site. Collapsed to one type they're indistinguishable in Rust. `worker/src/send_email.rs` keeps the [`EnvBinding`] impl on top of the auto-gen `SendEmail` extern type, plus a `#[cfg(test)]` compile check that `SendEmail: Send` (which it is already, via the upstream `JsValue: Send + Sync` change — no `unsafe impl Send` needed). * Use FixedLengthStream Deref instead of unchecked_into in mime-stream test `FixedLengthStream` already has `extends = web_sys::TransformStream` in `worker-sys`, so wasm-bindgen auto-generates `Deref<Target = TransformStream>` and `fixed.readable()` resolves through it. The previous `fixed.unchecked_into::<web_sys::TransformStream>().readable()` was unnecessarily defensive — drop the cast plus the now-unused `JsCast` and `web_sys` imports. * Fmt + advance ts-gen submodule to PR branch HEAD CI's rustfmt --check flagged the dispatch_structured signature. Apply fmt and bump the ts-gen submodule pointer to the latest PR #8 commit (CONVENTIONS.md rationale + emit cleanup). * Pull doc-comment generation from ts-gen PR #9 Each `new*` and `builder*` variant now ships with a doc block listing its inlined literal discriminants under `# Inlined fields` and the caller-supplied parameters under `# Parameters`, sourced from the original getter JSDoc. * Advance ts-gen submodule to merged main ts-gen PR #9 (doc comments on dictionary builder variants) merged. Bump the submodule pointer to the merge commit on main; the generated `worker/src/email.rs` is unchanged from the PR-branch output. * Advance ts-gen submodule to merged main ts-gen PR #10 (h2 headings + dash-separated bullets in builder docs) merged. Bump the submodule pointer and regenerate `worker/src/email.rs` with the updated doc format. --------- Co-authored-by: Guy Bedford <gbedford@cloudflare.com>

connyay requested a review from workers-devprod as a code owner April 17, 2026 03:08

workers-devprod added this to workers-sdk Apr 17, 2026

github-project-automation Bot moved this to Untriaged in workers-sdk Apr 17, 2026

workers-devprod requested review from a team and dario-piotrowicz and removed request for a team April 17, 2026 03:08

connyay mentioned this pull request Apr 17, 2026

feat(worker): add send_email binding support cloudflare/workers-rs#975

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Update packages/miniflare/src/workers/email/send_email.worker.ts

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Co-authored-by: devin-ai-integration[bot] <158243242+devin-ai-integration[bot]@users.noreply.github.com>

edevil approved these changes Apr 17, 2026

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Skye-31 reviewed Apr 17, 2026

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Comment thread packages/miniflare/test/plugins/email/index.spec.ts Outdated

dario-piotrowicz linked an issue Apr 17, 2026 that may be closed by this pull request

SendEmail.send returns a wrong type in development environment #13510

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dario-piotrowicz mentioned this pull request Apr 17, 2026

SendEmail.send returns a wrong type in development environment #13510

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actually match prod behavior

2df9c5c

connyay requested a review from Skye-31 April 17, 2026 18:28

dario-piotrowicz approved these changes Apr 20, 2026

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workers-devprod approved these changes Apr 20, 2026

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github-project-automation Bot moved this from Untriaged to Approved in workers-sdk Apr 20, 2026

dario-piotrowicz merged commit e456952 into cloudflare:main Apr 20, 2026
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github-project-automation Bot moved this from Approved to Done in workers-sdk Apr 20, 2026

workers-devprod mentioned this pull request Apr 20, 2026

Version Packages #13511

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connyay deleted the cjh/miniflare-send-email-result branch April 20, 2026 12:21

connyay added a commit to connyay/workers-rs that referenced this pull request Apr 20, 2026

remove miniflare workaround

73c632b

cloudflare/workers-sdk#13577 landed

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fix(miniflare): return EmailSendResult from send_email binding's send()#13577

fix(miniflare): return EmailSendResult from send_email binding's send()#13577
dario-piotrowicz merged 3 commits intocloudflare:mainfrom
connyay:cjh/miniflare-send-email-result

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