# Learn

- [What Is Email Verification? How It Works and What It Can't Tell You](https://www.emcheq.com/learn/what-is-email-verification): Email verification checks whether an address can receive mail without sending one: syntax, domain, mail servers and mailbox. Learn the checks and limits.
- [SPF, DKIM and DMARC Explained: How Email Authentication Works](https://www.emcheq.com/learn/spf-dkim-dmarc-explained): SPF lists who may send for your domain, DKIM signs messages, DMARC sets the policy. Learn the records, qualifiers, alignment and common mistakes.
- [How to Move DMARC From p=none to p=reject Safely](https://www.emcheq.com/learn/dmarc-none-to-reject): A step-by-step plan to move a domain from no DMARC to p=reject: publish p=none with reports, align every sender, then quarantine and reject safely.
- [Disposable Email Addresses: What They Are and How to Handle Them](https://www.emcheq.com/learn/disposable-email-addresses): Disposable email addresses are temporary inboxes. Learn why they appear in your data, how detection works and whether to block, flag or allow them.
- [Bounce Rate and Sender Reputation: Why List Hygiene Matters](https://www.emcheq.com/learn/bounce-rate-and-sender-reputation): Learn how hard and soft bounces and invalid addresses affect sender reputation, what verification can fix, and a simple list-hygiene routine.
- [Catch-All Domains and Role Accounts: Why They're Risky to Email](https://www.emcheq.com/learn/catch-all-and-role-accounts): Catch-all domains accept mail for any address, and role accounts like info@ are shared inboxes. Learn how verifiers treat them and what to do.

## Free tools
- [Free Email Verifier: Check If an Email Is Valid](https://www.emcheq.com/tools/email-verifier)
- [Free DMARC, SPF and MX Checker](https://www.emcheq.com/tools/dmarc-checker)
- [Free Email List Checker: Dedupe and Analyze](https://www.emcheq.com/tools/email-list-checker)