Making email images mobile-responsive is crucial due to the prevalence of mobile device usage for email access. To optimize image visibility, start by using a responsive email template provided by modern email service providers like Mailchimp or ConvertKit. These templates automatically adjust layout and image sizes for different screen widths. Implement the “fluid image” technique by setting images to 100% width of their container with a max-width to maintain proportionality on smaller screens and prevent layout distortion. Avoid embedding critical text within images to ensure readability and accessibility for all subscribers. Compress image file sizes for faster loading on slower mobile networks. Choose images with clear focal points that remain recognizable when scaled down for small screens. Lastly, thoroughly test your emails on various mobile devices and email clients before sending to guarantee optimal presentation across platforms.