List cleaning, also known as list hygiene, involves removing inactive, bounced, or unengaged email addresses from your list. This process is crucial because it: 1. Reduces Bounce Rates: Removing invalid email addresses decreases bounce rates. 2. Improves Deliverability: ISPs monitor bounce rates and spam complaints; keeping a clean list helps ensure your emails reach the inbox. 3. Enhances Engagement: Focusing on active subscribers improves engagement metrics and the overall effectiveness of your campaigns.