Avoiding over-emailing customers who already purchased can improve customer experience.

"So you might want to think about those who have purchased within the promo period. So if you have had someone already buy within the Black Friday... maybe you don't want to keep reminding them about your promotion."

Takeaway:

• Exclude customers who already purchased to prevent annoyance.
• Personalize follow-ups to recent customers with new recommendations.
• Maintaining customer satisfaction helps with retention.