Mailcheck

Spent a morning debugging why a client's emails kept landing in spam, only to find they had zero DNS auth records set up. That frustration turned into this CLI tool in Go that checks whether a domain has its email authentication configured properly. It takes domain names as input via stdin, one per line, and outputs a CSV report covering MX record presence, SPF policy status, and DMARC configuration. It is useful for auditing domains or verifying setup after making DNS changes.

The tool is written in Go using only the standard library, with DNS lookups performed via net package primitives and no external resolver dependencies. The clean CSV output is designed to be piped into other tools or spreadsheet apps for further processing.