Small things we needed while building email infrastructure, free and without an account.
The SPF, DKIM, and DMARC records a sending subdomain needs, with a policy you can actually support on day one.
Point it at a Streamable HTTP endpoint and see every tool the server exposes, with its arguments.
Drop an aggregate report and read it: who is sending as your domain, how much authenticates, and which sources are failing.
Count the DNS lookups an SPF record costs, including every nested include, and see which branch pushed it over ten.
Check what a domain publishes for SPF, DKIM, and DMARC, whether it is blocklisted, and what is wrong with any of it.
Paste an Authentication-Results header and see what passed, including the alignment check that decides DMARC.
Turn a target sending volume into a week by week ramp for a new domain, with the reply share the doubling rate depends on.
Real addresses on your own domain, threaded replies, and human oversight, over MCP.
3,000 emails a month, free, no credit card.