When you are importing CSV files, the following are our recommended default settings on the import page:

1. Character set of the file: UTF-8 Unicode
2. Separator used: Automatic
3. Filter blank email addresses: On (this will prevent importing rows that don't have an email address)
4. Allow invalid email address: Off (prevents malformed email addreses from being imported)
5. Display attribute warnings: up to you
6. Filter duplicate records: On
7. Duplicates are determined by: We recommend you use just email address, unless you have other attributes you know will ensure identification of duplicates