1. The file type must be CSV. If you manage your email list within an email service provider like MailChimp or Constant Contact, export your list as a CSV file. If your email list is in a XLS or XLSX file, follow these steps:
2. The first row of your CSV file must contain column headings, and the column that contains email addresses must have the column heading Email.
3. The file must contain no more than 2 million records.
Upload your file as a CSV or Microsoft Excel (.xls or .xlsx). See our file format guide