Domain Health

Email authentication and deliverability posture for any domain, using only dig and the standard library. No API key, no paid tool, no per-check cost.

The same DNS primitives serve two opposite jobs, which is why they live in one skill:

Defensive. Audit a domain you own before you send from it, and before you tighten a DMARC policy. Getting this wrong silently sends your own invoices and password resets to spam.

Offensive. Score a prospect's domain to find a real, specific gap worth opening a cold email with.

When to run it

Before starting outbound from any domain. Before changing a DMARC policy. When email is landing in spam and nobody knows why. When enriching a prospect list with a technical hook. After adding any new sending tool, because that is when sender inventory drifts.

Modes

Audit (default) runs against domains you own.