Accepted file formats and limits

For phase 1 onboarding, the safest supported formats are:

• .csv
• .xlsx
• .txt with one email per line

Before upload

Prepare the file so that:

• one column clearly contains the email addresses
• there are no duplicate headers inside the file
• there are no blank or comment-only rows

If you are still blocked

Read Upload Your First List for the full preparation flow.

If a file is within limits but still fails, open the support widget and include the file type and estimated row count.