Free tool
Free email checker — check if an email address is valid
Paste one address or a whole list. DebounceNow checks syntax, the top-level domain, live DNS and MX records, SPF/DMARC, disposable providers, role accounts and likely typos — then tells you who really hosts the mailbox. Free, unlimited, no API key.
Every check, in one pass
RFC-strict syntax, IANA TLD registry, DNS resolution, MX records including null MX and parked domains, SPF and DMARC, disposable lists, role patterns and gibberish scoring.
Know the mailbox provider
MX hosts are mapped to the real provider and to business versus free mailbox, so you can segment sends per provider and throttle where it matters.
Built for lists, not just one address
Import a CSV of any shape, dedupe automatically, watch results stream in, and export grouped CSVs for clean addresses, providers and company categories.
Want mailbox-level certainty?
The free checker removes addresses that can never deliver. To confirm a mailbox exists, run the SMTP debouncer with credits — or read the full guide to verifying an email address.
View credit packsEmail checker FAQ
The questions people ask most about checking whether an email address is valid.