Add per-mailbox "also forward a copy to" setting - #10
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Turbopack (Next.js 16's default bundler) produces server chunks that @opennextjs/cloudflare 1.19.11 cannot fully inline into the deployed worker bundle, causing ChunkLoadError/"handler is not a function" at runtime on every request. Webpack output builds and deploys cleanly. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Mailflare currently only supports storing inbound mail (the "forward"
routing action exists in the type system but resolveInboundAddress()
never returns it, and inbound.ts's handling of it is a no-op log
statement). There's no way to keep an external safety-net copy of a
mailbox's mail without moving off Mailflare's own routing rule.
This adds an optional forwardTo address per mailbox:
- New nullable mailboxes.forward_to column (migration 0011)
- Settable via mailbox creation (POST /api/mailboxes) and update
(PATCH /api/mailboxes/[id]), validated as an email address
- Surfaced in the mailbox settings UI ("Also forward a copy to")
- Wired into worker.ts's email() handler via a new
resolveForwardTarget() helper, calling the real
ForwardableEmailMessage.forward() API
Note on placement: the forward() call has to happen inside email()
itself, not the queue consumer that does the actual store/parse work
- Cloudflare only allows forward() for the duration of the handler
invocation that received the message, so it can't be deferred to
async queue processing. Forwarding therefore happens right after the
message is durably captured to R2 + enqueued, rather than waiting on
the full processing pipeline to succeed - which is arguably a safer
property for a "safety net" copy (the external forward isn't gated on
Mailflare's own processing succeeding).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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Summary
forwardToaddress per mailbox, settable at creation and via mailbox settings ("Also forward a copy to")worker.ts'semail()handler now calls the realForwardableEmailMessage.forward()API to send a safety-net copy to that address, alongside Mailflare's normal store/parse pipeline@opennextjs/cloudflare1.19.11 doesn't fully inline Turbopack's server chunks into the deployed Worker bundle — this surfaced as aChunkLoadError/"handler is not a function" 500 on every requestWhy this design
The codebase already had a
"forward"routing action in its type system (RoutingDecision.action), but it was unreachable dead code —resolveInboundAddress()never returns it, and where it's referenced ininbound.tsit's just aconsole.infono-op. There was no way to keep an external copy of a mailbox's mail without abandoning Mailflare's own Cloudflare Email Routing rule entirely.One constraint shaped the implementation:
ForwardableEmailMessage.forward()is only valid for the duration of theemail()handler invocation that received the message — it can't be called later from the queue consumer that does the actual store/parse work. So the forward has to happen inemail()itself, right after the message is durably captured to R2 and enqueued, rather than waiting on the full async processing pipeline to succeed. I think that's actually a better property for a "safety net" copy anyway — it isn't gated on Mailflare's own processing logic being bug-free.Test plan
npx tsc --noEmitshows no new type errors introduced by this change (two pre-existing errors in unrelated files remain, untouched by this PR)🤖 Generated with Claude Code