What file formats can I upload for bulk verification?

Two file formats work for bulk uploads:

• CSV (.csv) — the most common format. Export directly from Mailchimp, HubSpot, your CRM, or a spreadsheet. We preserve your other columns (names, signup dates, sources) alongside the verification results in the output.
• TXT (.txt) — one email per line, or comma/semicolon-separated. Useful when you just have a list of addresses without any other data.

Limits per upload

• Maximum 1,000,000 emails per upload
• Maximum 100 MB file size
• Larger lists need to be split into multiple uploads

What the file should look like

For CSV, your file can have other columns alongside the email column. We detect which column contains the emails and process them, returning the verification status and score in new columns appended to your original data.

Headers are optional but recommended. If you have a header row, we use it to label columns in the result file.

Or skip the file entirely

On the Bulk Upload page, the same form accepts pasted addresses directly into a text box. Newline-separated or comma-separated both work. Useful when you copy a list from somewhere and do not want the extra step of saving a file.