About the Email Syntax Checker
The Email Syntax Checker validates a list of addresses against RFC-style rules, flags likely domain typos (gmial.com, gmx.dee …) and marks duplicates — a quick pre-clean before importing into a mailing tool. For a live domain/MX check, use the Email Validator.
No — syntax checking catches format errors and typos. Whether the domain can receive mail requires an MX check (see the Email Validator).