SendGate — self-hosted open-source alternative to ZeroBounce / MillionVerifier

Source: Dev.to

Overview

About a month ago I open‑sourced Senlo. The project now has around 150 stars—modest numbers, but for my first OSS experience it feels great.

Why SendGate?

I was spending most of my time working on an email validation package. Since Senlo is now focused on transactional and product‑lifecycle emails, the validation logic no longer fits inside the main project. Rather than let it sit idle, I released it as a separate self‑hosted service called SendGate.

Features

• Lightweight, self‑hosted – runs on your own server, no database or external accounts required.
• Syntax & DNS checks – validates email syntax, looks up MX records, and inspects SPF/DKIM/DMARC configurations.
• Domain analysis – detects catch‑all domains, disposable providers, and role‑based addresses (e.g., info@, support@).
• Risk scoring – returns a simple risk score based on heuristics such as missing auth records, unusual MX setups, shared or suspicious infrastructure, and temporary‑looking domains.
• In‑memory processing – no email lists are stored; everything is processed in RAM.
• API & bulk mode – access via a small REST API or run bulk CSV checks locally.

Usage

SendGate is intended as a developer/internal utility rather than a full‑blown platform. You can:

1. Deploy the service on any server you control.
2. Query the REST endpoint for single‑email validation.
3. Run bulk checks by feeding a CSV file to the local command‑line tool.

Repository & Demo

• Repository: GitHub – SendGate
• Live demo: Demo instance

If you find it useful, a star or any feedback on GitHub would mean a lot.