Also known as: Format Check
The most basic email check: confirming an address is correctly formatted before any network lookups.
Syntax validation is the first and cheapest verification step: does the string even look like an email address? It checks for a single @, a valid local part, a plausible domain, and conformance to the email format rules (RFC 5321/5322), including length limits.
It is necessary but nowhere near sufficient. [email protected] is perfectly valid syntax for a mailbox that does not exist. Syntax checks catch typos and malformed input, but cannot tell you whether an address can actually receive mail.
That is why real verification continues past syntax into MX and SMTP checks. A good engine also offers typo correction — suggesting gmail.com when someone types gmial.com — to rescue addresses that are simply mistyped.
The process of checking whether an email address is real, correctly formatted, and able to receive mail before you send to it.
A DNS record that tells other servers which mail server is responsible for receiving email for a domain.
The standard protocol mail servers use to send and receive email across the internet.
See it in action
Check any address against BounceShift's multi-layer engine — syntax, MX, disposable, and role checks free, with full SMTP verification on signup.