To improve email deliverability, newsletter senders must address several key areas. Authentication through SPF, DKIM, and DMARC is crucial, alongside monitoring sender reputation using tools and feedback loops. Implementing feedback loops helps manage complaints and maintain list hygiene. Validating email addresses and regularly cleaning lists minimizes bounce rates. Content should be relevant to subscribers' expectations, and email volume should be throttled, especially when starting new campaigns. IP addresses must be warmed up gradually. Segmentation enables targeted content, while avoiding spam trigger words, providing preference centers, optimizing for mobile, using double opt-in, ensuring consistent sender information, and A/B testing further enhance deliverability.