Email Address Validator

This tool inspects an address in three non-intrusive layers. First, syntax: it checks that the string is shaped like an address with a local part, an @ sign, and a domain — the same pattern RFC 5321 and RFC 5322 describe, though like most validators it uses a practical regex rather than the full grammar, so a handful of exotic-but-legal forms (quoted local parts, IP-literal domains) may be rejected. Second, DNS: it performs an MX (mail exchanger) lookup on the domain and lists the returned records with their priority values and exchange hostnames. If a domain publishes no MX records, mail servers usually cannot deliver to it, so the address is flagged undeliverable. Third, reputation: it compares the domain against a list of known disposable or throwaway providers (such as 10-minute-mail services) and warns you when it matches. The combined result is a probabilistic verdict — likely deliverable or likely undeliverable — not a guarantee. Only the receiving mail server knows for certain whether a specific mailbox exists, and confirming that would require an SMTP handshake or a sent message, which this tool deliberately avoids.