# Technical Documentation: reacherhq/backend > ℹ️ **Provenance:** Standard README.md · [CodeWiki Reference](https://codewiki.google/github.com/reacherhq/backend) · Recency: Active (< 180 days) [](https://github.com/reacherhq/backend/actions) [](https://github.com/sponsors/amaurym)

⚙️ Reacher Backend

Backend Server for Reacher Email Verification API: https://reacher.email.

# ⚠️⚠️ IMPORTANT UPDATE ⚠️⚠️ This repo has been moved to the monorepo [reacherhq/check-if-email-exists](https://github.com/reacherhq/check-if-email-exists), in the `backend` subfolder. ## Reacher Backend This repository holds the backend for [Reacher](https://reacher.email). The backend is a HTTP server with the following components: - [`check-if-email-exists`](https://github.com/reacherhq/check-if-email-exists), which performs the core email verification logic, - [`warp`](https://github.com/seanmonstar/warp) web framework. ## Get Started There are 2 ways you can run this backend. ### 1. Use Docker The [Docker image](./Dockerfile) is hosted on Docker Hub: https://hub.docker.com/r/reacherhq/backend. To run it, run the following command: ```bash docker run -p 8080:8080 reacherhq/backend ``` You can then send a POST request with the following body to `http://localhost:8080/v0/check_email`: ```js { "to_email": "someone@gmail.com", "from_email": "my@my-server.com", // (optional) email to use in the `FROM` SMTP command, defaults to "user@example.org" "hello_name": "my-server.com", // (optional) name to use in the `EHLO` SMTP command, defaults to "localhost" "proxy": { // (optional) SOCK5 proxy to run the verification through, default is empty "host": "my-proxy.io", "port": 1080 }, "smtp_port": 587 // (optional) SMTP port to do the email verification, defaults to 25 } ``` ### 2. Run locally If you prefer to run the server locally on your machine, just clone the repository and run: ```bash cargo run ``` The server will then be listening on `http://127.0.0.1:8080`. ### Configuration These are the environment variables used to configure the HTTP server: | Env Var | Required? | Description | Default | | ----------------------------------- | --------------------------- | ---------------------------------------------------------------------------------------------------------- | ------------------ | | `RCH_ENABLE_BULK` | No | If set to 1, then bulk verification endpoints will be added to the backend. | 0 | | `DATABASE_URL` | Yes if `RCH_ENABLE_BULK==1` | Database connection string for storing results and task queue | not defined | | `RCH_HTTP_HOST` | No | The host name to bind the HTTP server to. | `127.0.0.1` | | `PORT` | No | The port to bind the HTTP server to, often populated by the cloud provider. | `8080` | | `RCH_FROM_EMAIL` | No | The email to use in the `MAIL FROM:` SMTP command. | `user@example.org` | | `RCH_SENTRY_DSN` | No | If set, bug reports will be sent to this [Sentry](https://sentry.io) DSN. | not defined | | `RCH_DATABASE_MAX_CONNECTIONS` | No | Connections created for the database pool | 5 | | `RCH_MINIMUM_TASK_CONCURRENCY` | No | Minimum number of concurrent running tasks below which more tasks are fetched | 10 | | `RCH_MAXIMUM_CONCURRENT_TASK_FETCH` | No | Maximum number of tasks fetched at once | 20 | | `RUST_LOG` | No | One of `trace,debug,warn,error,info`. 💡 PRO TIP: `RUST_LOG=debug` is very handful for debugging purposes. | not defined | ## REST API Documentation Read docs on https://help.reacher.email/rest-api-documentation. The API basically only exposes one endpoint: `POST /v0/check_email` expecting the following body: ```js { "to_email": "someone@gmail.com", "from_email": "my@my-server.com", // (optional) email to use in the `FROM` SMTP command, defaults to "user@example.org" "hello_name": "my-server.com", // (optional) name to use in the `EHLO` SMTP command, defaults to "localhost" "proxy": { // (optional) SOCK5 proxy to run the verification through, default is empty "host": "my-proxy.io", "port": 1080 }, "smtp_port": 587 // (optional) SMTP port to do the email verification, defaults to 25 } ``` Also check [`openapi.json`](./openapi.json) for the complete OpenAPI specification. ## License `reacherhq/backend`'s source code is provided under a **dual license model**. ### Commercial license If you want to use `reacherhq/backend` to develop commercial sites, tools, and applications, the Commercial License is the appropriate license. With this option, your source code is kept proprietary. Purchase an `reacherhq/backend` Commercial License at https://reacher.email/pricing. ### Open source license If you are creating an open source application under a license compatible with the GNU Affero GPL license v3, you may use `reacherhq/backend` under the terms of the [AGPL-3.0](./LICENSE.AGPL). [Read more](https://help.reacher.email/reacher-licenses) about Reacher's license. ## Sponsor my Open-Source Work If you like my open-source work at Reacher, consider [sponsoring me](https://github.com/sponsors/amaurym/)! You'll also get 8000 free email verifications every month with your Reacher account, and a this contribution would mean A WHOLE LOT to me. --- METRICS --- - Files Extracted: 1 - Estimated Token Budget: ~1353 tokens - Recency Window: Active (< 180 days) - Canonical Reference: https://codewiki.google/github.com/reacherhq/backend