The `check-if-email-exists` repository provides a Rust-based tool designed to verify the existence and deliverability of email addresses without actually sending an email. The project includes multiple ways to interact with it, including a CLI binary, a programmatic library for Rust projects, and a Dockerized HTTP backend that offers various verification features such as syntax validation, MX record checking, and SMTP server verification.
- Offers several modes: via CLI, through a Rust crate dependency, or using an HTTP/Docker backend.
- Verifies multiple properties including reachability status, disposable email detection, role account identification, and Gravatar URLs.
- Includes checks for "Have I Been Pwned?" to see if an email has been compromised in data breaches.
Jonas Kaninda writes that Posta is a self-hosted, developer-first email platform handling outbound, inbound, and relayed email through a single HTTP API, with SMTP available where needed. It positions itself as a fully self-hostable alternative to SendGrid, Mailgun, and Postmark, giving teams ownership of their email infrastructure, data, and deliverability.
- Ships as a single Go binary in two modes (server and worker); all state lives in PostgreSQL, Redis, and optional S3-compatible object storage.
- Includes a Vue 3 dashboard, web form ingest with spam scoring, A/B campaign testing, RFC 8058 one-click unsubscribe, and Prometheus metrics.- Official SDKs for Go, PHP, Java, and .NET; also deployable as a managed template on Miabi.
- Requires Go 1.27+, PostgreSQL, and Redis