ESPs manage internal and client deliverability responsibilities using a multi-faceted approach that includes dedicated teams or individuals, proactive monitoring, adherence to standards, the provision of tools and consultation, and a strong focus on reputation management. They ensure their own internal emails are delivered successfully while also providing clients with the necessary support and resources to optimize their campaigns. Key to this is maintaining a robust infrastructure, managing shared IP reputation carefully, and operating a responsive abuse desk. Following best practices, such as segmentation, authentication, and feedback loops, is essential. Moreover, ESPs leverage various tools, including those provided by Google, Microsoft, and SendGrid, to monitor performance and address deliverability issues.