When using tailored audiences from customer lists, what is the single greatest compliance risk to avoid?

When using tailored audiences from customer lists, the single greatest compliance risk to avoid is using data obtained without proper consent for advertising purposes. This directly violates privacy regulations like GDPR (General Data Protection Regulation) and CCPA (California Consumer Privacy Act). 'Tailored audiences' are created by uploading customer information (e.g., email addresses) to X to target those specific individuals with ads. If you don't have explicit consent from those customers to use their data for advertising, you are breaking the law and potentially facing hefty fines. For instance, simply having a customer's email address because they made a purchase doesn't automatically grant you permission to use it for advertising on X. You need to have obtained clear, affirmative consent for that specific purpose. Failing to do so can lead to serious legal and reputational consequences.