Rightfully received data
GDPR requires you to make sure you only process lawfully obtained data. Contacts that fill out an opt-in form in Flexmail have given you permission to store their personal data. However when you're importing a file of contacts into Flexmail, you need to make sure you have a legal right to store that data. That's why we ask you to indicate you do during the import.
More information on the legal bases for the processing of personal information under the GDPR can be found here.