99882bb80a
Prevents the form being abused as an open email relay to arbitrary addresses (which is the realistic abuse vector — disk fill, server compromise, and device exploitation are all bounded already). Default allowlist: kindle.com, pbsync.com. Suffix matching so subdomains (e.g. free.kindle.com) are also accepted. Configurable via ALLOWED_READER_DOMAINS env var so the list can be extended without code changes.
142 lines
4.6 KiB
Markdown
142 lines
4.6 KiB
Markdown
# Send to E-Reader
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Convert web articles to EPUB and email them straight to your e-reader. Works with any device that accepts emailed files — Kindle, PocketBook, or anything else with a similar service.
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Built with Express 5 + TypeScript. Hosted at [read.atanasov.fi](https://read.atanasov.fi).
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## How it works
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Two ways to send something to your e-reader:
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**URL → EPUB**
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1. You paste an article URL and your e-reader's email address.
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2. The server fetches the page, runs Mozilla Readability over it to strip ads/chrome, builds an EPUB, and emails it to the address you gave.
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3. The EPUB is deleted from the server immediately after sending.
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**Upload a file**
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1. Drag (or pick) a file — EPUB, PDF, MOBI, anything your device accepts.
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2. The server attaches it to an email and sends it to your e-reader as-is, no conversion.
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3. The file is deleted from the server immediately after sending. Max size: 25 MB.
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## Supported devices
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The destination email domain is checked against an allowlist (default: `kindle.com`, `pbsync.com`) to prevent the app being used as an open email relay. Subdomains count, so `free.kindle.com` works too.
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| Device | Email pattern |
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|---|---|
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| Amazon Kindle | `*@kindle.com` (or `*.kindle.com` subdomains) |
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| PocketBook | `*@pbsync.com` |
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You can extend the list via the `ALLOWED_READER_DOMAINS` env var (see below).
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You'll also need to add the **sender** address to your device's approved-senders list — one-time per device.
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## Prerequisites
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- Node.js 20 or newer
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- An SMTP-capable email provider. Defaults are set up for [Resend](https://resend.com) — sign up (no waitlist), verify your domain, grab an API key.
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## Local development
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```bash
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git clone <your-fork>
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cd send_to_kindle
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npm install
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cp .env.example .env # then fill in SMTP_PASSWORD (Resend API key) and MAIL_FROM
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npm run dev
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```
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Server listens on `http://localhost:3000` (override with `PORT`).
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## Production build
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```bash
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npm run build
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npm run start
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```
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## Environment variables
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| Variable | Required | Default | Notes |
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|---|---|---|---|
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| `SMTP_HOST` | no | `smtp.resend.com` | Any SMTP server works |
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| `SMTP_PORT` | no | `587` | `587` = STARTTLS (preferred — port 465 is blocked by most VPS providers) |
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| `SMTP_USER` | yes | — | For Resend, literally the string `resend` |
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| `SMTP_PASSWORD` | yes | — | For Resend, your API key (`re_…`) |
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| `MAIL_FROM` | yes | — | Sender address, e.g. `read@atanasov.fi`. Must be from a verified domain on your provider. |
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| `ALLOWED_READER_DOMAINS` | no | `kindle.com,pbsync.com` | Comma-separated allowlist of destination email domains. Suffix-matching, so subdomains are allowed. |
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| `PORT` | no | `3000` | Listen port |
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## Resend setup (quick)
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1. Sign up at [resend.com](https://resend.com).
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2. Add your domain (e.g. `atanasov.fi`) and add the SPF/DKIM/return-path DNS records they generate. Verification usually completes in a few minutes.
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3. Create an API key.
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4. In `.env`:
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```
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SMTP_USER=resend
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SMTP_PASSWORD=re_xxxxxxxxxxxxxxxxxx
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MAIL_FROM=send@read.atanasov.fi
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```
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For a different provider, just point `SMTP_HOST` / `SMTP_PORT` / `SMTP_USER` / `SMTP_PASSWORD` at it — any standard SMTP service works.
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## API
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### `POST /send-article`
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Body (JSON):
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```json
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{
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"url": "https://example.com/article",
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"readerEmail": "your-device@kindle.com"
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}
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```
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Response on success:
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```json
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{
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"success": true,
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"message": "Article sent to your e-reader",
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"title": "Article Title"
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}
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```
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### `POST /send-file`
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Body (multipart/form-data):
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- `file` — the binary file (max 25 MB)
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- `readerEmail` — destination address
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Response on success:
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```json
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{
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"success": true,
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"message": "File sent to your e-reader",
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"title": "original-filename.epub"
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}
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```
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### Rate limit
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Both endpoints share a limit of **20 sends per IP per hour**.
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## Limitations
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- Articles must be publicly accessible — no paywalled or login-required pages.
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- Server-side fetch means JS-heavy SPAs may extract poorly (the page must render meaningful HTML without JavaScript).
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- Some sites block non-browser user-agents; the app sends a Chrome UA but can still be refused.
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## Stack
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- [Express 5](https://expressjs.com/) — HTTP server
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- [@mozilla/readability](https://github.com/mozilla/readability) — article extraction
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- [jsdom](https://github.com/jsdom/jsdom) — DOM for Readability
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- [@lesjoursfr/html-to-epub](https://github.com/lesjoursfr/html-to-epub) — EPUB generation
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- [nodemailer](https://nodemailer.com/) — SMTP client
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- [multer](https://github.com/expressjs/multer) — multipart/form-data upload parsing
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- [express-rate-limit](https://github.com/express-rate-limit/express-rate-limit) — per-IP rate limiting
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## License
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GPL-3.0-only. See [LICENSE](LICENSE).
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