Check if email addresses have valid format - instantly, for free, right in your browser. No emails are sent to any server. Everything runs client-side.
This free tool validates email address syntax (format) based on RFC 5322 standards. It checks for common formatting errors that would cause emails to bounce immediately.
Every valid email must have exactly one @ symbol separating the local part from the domain.
Checks that the part before @ contains only allowed characters and doesn't start/end with dots.
Verifies the domain uses valid characters, has a proper top-level domain (like .com), and follows DNS naming rules.
Ensures the local part doesn't exceed 64 characters and the total address stays within 254 characters.
Detects spaces, tabs, or other whitespace that would make the email invalid.
Catches consecutive dots, missing parts, and other structural issues that indicate a malformed address.
Syntax checking is the first layer of email validation. It catches obvious formatting errors, but a syntactically valid email might still bounce if the domain doesn't exist or can't receive mail.
| Check | This Tool | BounceBuster App |
|---|---|---|
| Email format/syntax | ||
| Domain existence (DNS) | ||
| MX record verification | ||
| Bulk CSV/Excel processing | ||
| Detailed bounce reports | ||
| Export clean lists | ||
| 100% local processing |
Download BounceBuster - it runs locally on your computer, validates format + DNS + MX records, and catches roughly 90% of bounce-causing addresses.
One-time $19 for unlimited validation. No uploads, no per-email fees, no monthly subscriptions. Your email lists never leave your machine.