Email list cleaning services, according to documentation from various providers (SendGrid, ZeroBounce, Kickbox, and Mailchimp), improve email deliverability by removing invalid, inactive, or harmful email addresses. This process reduces bounce rates and spam complaints, which are essential factors in maintaining a positive sender reputation. List cleaning also often includes syntax checks, domain validation, mailbox existence verification, and spam trap detection. The result is a healthier email list, better campaign performance, and improved engagement metrics.