The Postmark product update for October 2016 includes several major features such as domain verification, link tracking, and new templates. Domain verification allows users to verify the domains they send emails from, improving deliverability and authentication. Link tracking enables users to track link clicks within emails, providing valuable insights into email performance. New templates have been added, including best practices guides and starter templates that can be used in Postmark or elsewhere. The update also includes performance improvements, such as upgrading RabbitMQ to v3, which has boosted response times and stability. Additionally, bug fixes have been addressed, including issues with inline images and tracking pixel display in Gmail. Future plans include advanced permissions, 2-factor authentication, and enhancements to bounce webhooks, among other features.