In this lesson, you will learn about email sender reputation, which is a score given by inbox providers like Gmail, Yahoo, and Outlook that determines if your emails reach recipients' inboxes or are marked as spam. To improve your email sender reputation, you should maintain a clean mailing list by only emailing opted-in contacts and regularly updating your list to remove inactive or invalid addresses. Personalize and segment your emails to ensure they are relevant and engaging for different audience segments, and authenticate your emails using standards like SPF, DKIM, and DMARC to verify your identity and reduce the risk of being marked as spam.