# MailSetupCheck

> Check your domain's email setup so your messages reach the inbox.

Written by one author, a Principal ML engineer (10+ years in machine learning, from research to production; Former Staff ML Engineer working on document extraction and OCR; Former Lead ML Platform Engineer for a 5,000-stream computer-vision platform; Contributor to vLLM; creator of Videoflow (1,000+ GitHub stars)). The tools run in the browser and never upload files. Every page has a Markdown version at the same path with .md appended.

## Tools

- [Cold email cost calculator: inboxes, domains, warmup and monthly cost](https://mailsetupcheck.com/cold-email-cost-calculator.md): How many inboxes and sending domains a cold-email target needs, how long warmup takes before you reach full volume, and what each mailbox and sequencer combination costs per month and per 1,000 emails. Prices come from each vendor's own pricing page, with the date read.

## Guides

- [Cold email that stays legal: CAN-SPAM in plain English](https://mailsetupcheck.com/cold-email-can-spam.md): What US law requires of every commercial email, business-to-business included, what each violation can cost, what makes a violation "aggravated", and the mailbox providers' rules on top. Quoted from the FTC, the CFR and the US Code. Not legal advice.
- [DMARC p=none to reject: a safe rollout](https://mailsetupcheck.com/dmarc-p-none-to-reject.md): How to move DMARC from monitoring (p=none) to quarantine and reject without blocking your own mail. What each policy does, how to read reports, what changed with RFC 9989 in 2026 (pct is gone, t=y is new), and how to roll back.
- [Gmail and Yahoo bulk sender requirements explained (and Microsoft's)](https://mailsetupcheck.com/gmail-yahoo-bulk-sender-requirements.md): What Gmail, Yahoo and Microsoft's Outlook.com require from senders in 2026, who counts as a bulk sender, which rules apply to everyone, and what happens when you miss. Read from each provider's own pages, with a checker for the parts DNS can show.
- [How the MailSetupCheck checker and calculator work](https://mailsetupcheck.com/methodology.md): Every rule the email setup checker applies and the standard it comes from, what it can and cannot see from DNS, the DKIM selectors it tries, how it recognizes mail providers, and where the cost calculator's prices come from.
- [SPF too many DNS lookups: how to fix it](https://mailsetupcheck.com/spf-too-many-dns-lookups.md): Why SPF stops at 10 DNS lookups, which parts of the record count, how many lookups common email services cost (measured), and the fixes in order of safety, from deleting dead includes to moving a sender to a subdomain.

## Optional

- [About MailSetupCheck and its author](https://mailsetupcheck.com/about.md): Who builds MailSetupCheck, the credentials behind it, how the site is funded, and how to report a wrong result, a changed rule or a wrong price.
- [Affiliate disclosure](https://mailsetupcheck.com/affiliate-disclosure.md): How MailSetupCheck may earn money from referral and affiliate links, how those links are labeled, the rules that keep commissions out of the checker's findings and the calculator's rankings, and the current list of relationships.
- [Privacy](https://mailsetupcheck.com/privacy.md): The MailSetupCheck checker sends DNS questions from your browser to a public DNS resolver, never to this site. The calculator sends nothing. The site sets no cookies and has no accounts. What each resolver receives, and what it keeps.