Common causes
- Missing @ sign or a missing domain part.
- Spaces, commas or brackets inside the address.
- Two @ signs or two dots in a row.
- Text pasted from a form or PDF that added extra characters.
How to fix it
- Correct the address if the mistake is obvious, for example a stray space.
- Remove it if you cannot tell what was intended.
- Use a real email input type on your forms so bad text is caught early.
- Run lists through a syntax check before sending.
How to prevent it Take the address off your list and verify the rest before the next send.
Frequently asked questions
Can a verifier fix the address?
It can flag common typos in the domain and suggest a correction, but it never changes your data on its own.
Does Mailcut charge for these?
Addresses that fail the syntax check are reported as Invalid in the result file, with the reason "invalid syntax".