Email Validator
Two-stage validation: RFC 5322 syntax check, then a live MX record lookup.
How email validation works
Validation happens in two stages, each catching a different class of problem. The syntax check applies RFC 5322 rules to confirm the address is structurally well-formed — no missing @ symbol, no invalid characters, no obviously broken format. This is instant and requires no network access. The MX record check then queries DNS live to confirm the domain actually has mail servers configured to accept email, catching typos and non-existent domains that would otherwise slip past a syntax-only check.
Neither stage can confirm a specific mailbox exists — that would require attempting actual delivery, which risks false negatives from servers that don't support real-time verification and can trigger spam-prevention measures. This two-stage approach is the standard trade-off used by most production email validation: catch the vast majority of invalid addresses cheaply, without the cost and fragility of full delivery verification.
Frequently asked questions
- What does the MX record check actually verify?
- That the domain has at least one Mail Exchanger (MX) DNS record — meaning mail servers exist that could receive email for that domain. It doesn't confirm the specific mailbox exists, only that the domain is set up to receive mail at all.
- Why is the MX result cached by domain, not by full address?
- Every address at the same domain (e.g. alice@example.com and bob@example.com) shares the same MX records, so caching by domain avoids a redundant DNS lookup for each one.
- What common typos does the suggestion catch?
- Frequent domain misspellings like gmial.com, yaho.com, and hotmal.com — mapped to their correct gmail.com/yahoo.com/hotmail.com equivalents.
- What is syntax validation vs MX record validation?
- Syntax validation checks that the address is a well-formed string according to RFC 5322 (correct use of @, valid characters, proper structure) — this is a purely local, offline check. MX record validation goes further and checks live DNS to confirm the domain actually has mail servers configured to receive email at all.
- Can an email pass validation but still bounce?
- Yes — passing both syntax and MX checks confirms the address is well-formed and the domain can receive mail in general, but it doesn't confirm that specific mailbox exists. An address can look completely valid and still bounce if the mailbox itself was never created or has been deleted.
- What are common email format mistakes?
- Missing the @ symbol, extra spaces, missing the domain extension (e.g. "user@example" instead of "user@example.com"), and typos in well-known domains (gmial.com instead of gmail.com) are among the most frequent — this tool's suggestion feature catches the last category automatically.
- What is a disposable email address?
- A disposable (or "temporary") email address is one created via a service specifically for short-term, throwaway use — often to sign up for something without revealing a real address. Disposable addresses typically pass both syntax and MX validation since they are technically functional, so detecting them requires checking against a list of known disposable-email domains, which this tool does not do.