Definition
Email validation: Checks that an address is correctly formatted and that its domain is set up to receive mail, without contacting the mailbox. It catches typos and dead domains but cannot tell whether a specific mailbox exists.
What email validation checks
Syntax first: one @ sign, a local part of at most 64 characters, no consecutive dots outside quotes, a valid domain name. Then the domain: does it exist in DNS, and does it publish MX records or another mail route.
Good validation adds typo detection for common misspellings such as gmial.com or a .con ending, and flags disposable domains, both of which pass a pure syntax check.
Email validation vs email verification
Validation answers whether an address could work. Verification answers whether it does, by asking the mail server about that specific mailbox.
An address like jane.doe@example.com at a real company passes validation even if Jane left two years ago. Only the SMTP check reveals that the mailbox is gone.
Why a regex is not enough
Simple patterns reject valid addresses, such as plus addresses, apostrophes in names and internationalized domains, which costs you real signups.
They also accept addresses that can never work: jane@gmial.com is perfectly formed. Syntax rules are only the first layer.
jane.doe@example.com valid syntax, domain has MX records
jane.doe+news@example.com valid syntax, plus address (RFC 5233)
jane..doe@example.com invalid: consecutive dots in the local part
jane@example.con valid syntax, but .con is not a real TLD
jane@gmial.com valid syntax, likely a typo of gmail.comHow RocketVerifier handles it
Our free email syntax checker and free email verifier run syntax, domain, MX and disposable checks without using credits. In the API, typo detection uses curated misspelled domains such as gmial.com, bad endings such as .con and edit distance, and returns the suggested fix in did_you_mean. Every paid verification then adds the live SMTP mailbox check that validation leaves out.