✦ClaudeProduct

Migrate transactional email to Cloudflare Email

levelsio's full agent prompt to audit and migrate transactional email to Cloudflare Email Service.

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levelsio's full agent prompt to audit and migrate transactional email to Cloudflare Email Service.

The prompt

✦Claude Code / Cursor

1	# Prompt: Migrate transactional email to Cloudflare Email Service
2
3	Paste this into Claude Code (or Cursor, or any agent) running inside your project.
4
5	---
6
7	I want to migrate this codebase's outbound email from its current provider (Postmark / SES / Resend / SendGrid / Mailgun / etc.) to Cloudflare Email Service (public beta, launched April 2026). Help me do this carefully.
8
9	## Context: what Cloudflare Email Service is
10
11	A new transactional email API from Cloudflare. Endpoint:
12
13	```
14	POST https://api.cloudflare .com/client/v4/accounts/{ACCOUNT_ID}/email/sending/send
15	Authorization: Bearer {API_TOKEN}
16	Content-Type: application/json
17	```
18
19	Request body:
20
21	```json
22	{
23	"to": "user@example.com", // string OR array of strings
24	"from": "no-reply@yourdomain.com", // string OR {"address":"x@y","name":"Display"}
25	"subject": "...",
26	"html": "<p>...</p>", // optional
27	"text": "...", // optional (one of html/text required)
28	"cc": ["..."], // optional, array
29	"bcc": ["..."], // optional, array
30	"reply_to": "...", // optional, single string
31	"headers": {"List-Unsubscribe": "<...>"} // optional, e.g. for newsletters
32	}
33	```
34
35	Success response: HTTP 200 + `{"success":true,"result":{"delivered":[],"queued":[],"permanent_bounces":[]}}`.
36
37	Failure: non-200 OR `success:false` OR non-empty `permanent_bounces`. Always check all three.
38
39	Pricing: $5/mo Workers Paid plan + 3,000 emails free + $0.35 per 1k after. Roughly 5× cheaper than Postmark. No batch send endpoint — loop single sends.
40
41	## Steps you should follow
42
43	### 1. Verify prerequisites with me
44
45	Before writing any code, ask me to confirm:
46
47	- I have a Cloudflare Workers Paid plan ($5/mo)
48	- I've onboarded my sender domain(s) in Cloudflare dashboard → Email → Email Sending → Onboard Domain (this auto-adds SPF/DKIM/DMARC + cf-bounce MX records)
49	- I have an API token with `email_sending:write` scope (created at http://dash.cloudflare.com/profile/api-tokens → Custom Token)
50	- I have my Cloudflare account ID
51
52	Don't proceed until you have these.
53
54	### 2. Recommend a domain reputation strategy
55
56	Most apps should split senders across 2-3 subdomains so spam complaints on one don't drag down deliverability on others:
57
58	- `mail.<domain>` or `members.<domain>` → transactional (login, receipts, password reset, in-app notifications)
59	- `e.<domain>` → cold/recovery (abandoned cart, win-back campaigns)
60	- `newsletter.<domain>` → opt-in newsletters with List-Unsubscribe headers
61
62	Each subdomain needs to be onboarded separately in Cloudflare. Ask me which I want.
63
64	### 3. Audit existing email sends
65
66	Use grep/search to find every place in this codebase that sends email. Look for:
67
68	- The current provider's SDK class names, API URLs, env/config vars
69	- Generic patterns like `mail()`, SMTP usage, `nodemailer`, etc.
70
71	Group findings by email type/purpose (e.g. "magic-link login", "payment receipt", "weekly newsletter") rather than by file. Tell me what you found before changing anything.
72
73	### 4. Add a single helper function
74
75	Don't sprinkle Cloudflare API calls across the codebase. Add one helper (provider-specific name like `sendEmailViaCloudflare()`) that:
76
77	- Defaults `from` from a config var (don't hardcode)
78	- Parses `"Name <email@domain>"` strings into the API's `{address, name}` object form
79	- Accepts `cc`/`bcc` as either string or array
80	- Accepts a `headers` dict (newsletters need `List-Unsubscribe` + `List-Unsubscribe-Post`)
81	- Returns `bool` (true on success, false on any failure)
82	- On failure, logs/alerts somewhere I can see (Telegram, Sentry, log file — match what the codebase already does)
83	- Sets curl/fetch timeouts (5s connect, 15s total) so a stuck CF API can't hang the request
84	- Treats `permanent_bounces: [...]` non-empty as a soft failure
85
86	### 5. Migrate one low-stakes email type first
87
88	Don't migrate everything at once. Pick the lowest-stakes email type in the audit (something where landing in spam wouldn't lose me money or users — e.g. "internal admin alert", "profile photo rejection") and migrate just that one. Test it end-to-end. Confirm the email actually arrives. Only then propose the next migration.
89
90	### 6. Stop me from migrating login email yet
91
92	If my codebase sends magic-link login or password-reset emails, do not migrate those to Cloudflare yet. Cloudflare Email Service is brand new (~1 month old at writing). Its IP/domain reputation is unproven. Login emails landing in spam = users locked out. Keep those on the current provider until at least 3 months of clean deliverability data on the lower-stakes types. Tell me this explicitly.
93
94	### 7. Suggest commit boundaries
95
96	After each successful migration, suggest a focused git commit with a clear message. Don't bundle unrelated changes.
97
98	## Important caveats to surface to me
99
100	- Beta product. Pricing isn't fully finalized. SLA undefined. Could change.
101	- No batch endpoint. Mass sends (newsletters to 1000+ recipients) need a loop — at ~150ms/send that's ~2.5min per 1000. Fine for crons, bad for sync user-facing flows.
102	- No bounce webhooks yet. Surface failures via the response body's `permanent_bounces` array.
103	- Suppression list auto-managed. Hard bounces, repeated soft bounces, and spam complaints get blocked. Spam-complaint suppressions are hard to remove (anti-abuse).
104	- No per-message logs/dashboard yet. Use the response's `messageId` for tracking if I need it.
105	- List-Unsubscribe headers are passed through verbatim — Gmail's bulk-sender requirement still met, but only if I include them in `headers`.
106
107	## Your first action
108
109	Before writing any code: do step 1 (ask for prerequisites) and step 3 (audit existing sends), then propose the migration order with a brief explanation of the reasoning. Wait for my confirmation before making changes.

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