How a message arrives

What happens between someone pressing send and the message appearing in your dashboard.

1. Email Routing accepts it

Your domain’s MX records point at Cloudflare. Setup enables Email Routing and sets the catch-all action to the mailriz Worker, so every address on the domain reaches the same handler.

The catch-all is not an ordinary routing rule — it has its own endpoint and is updated rather than created.

2. The Worker resolves the alias

The recipient is split into local part and domain. A +tag is stripped first, so news+netflix@ resolves to the alias news.

Then, in order:

1. Alias exists and is enabled → accept.
2. Alias exists but is disabled → reject. The catch-all does not resurrect an address you switched off.
3. No alias → create one, provided the domain is yours, the local part is valid, and the daily budget for auto-created aliases is not spent.

Rejections happen with setReject(), at the SMTP level. The sender gets a bounce and nothing is stored — spam that guesses addresses costs you no storage.

3. The raw message is stored first

Before anything is parsed, the complete .eml goes to the raw R2 bucket. If parsing fails afterwards, the original still exists — nothing is lost to a malformed message.

4. Parsing and storage

Using postal-mime:

• Attachments → the attachments bucket. Content-ID is recorded for each, which is what lets embedded images resolve later.
• HTML body → active content stripped (<script>, on* handlers, javascript: URLs), then stored as-sent in the HTML bucket. Presentation is left untouched.
• Remote images are counted at this point, so the reading pane knows whether to offer “show images” without inspecting the body again.
• Text body and snippet → D1.

5. The row, and the index

One row in emails, with a database trigger keeping the FTS5 index in sync — so search never needs a separate write path that could drift.

6. You see it

If the dashboard is open, an SSE connection notices within about four seconds and the list reloads. See Live updates.

Size limits

Cloudflare Email Routing accepts messages up to 25 MB. Larger ones are rejected before reaching the Worker; that limit is Cloudflare’s, not MailRiz’s.

On Workers Free, the 10 ms CPU budget per request can be exceeded while parsing a large HTML message, which makes inbound delivery fail intermittently. This is the main reason Workers Paid is recommended.