To design mobile friendly buttons, consider the following tips: 1. Use Touchable Area: Ensure the button has a generous touchable area. Even if the visual element is smaller, the clickable area should be at least 44x44 pixels. 2. Prioritize Placement: Place buttons where they are easily accessible, typically towards the center or bottom of the email. 3. Optimize for One-Handed Use: Many users operate their phones with one hand, so position buttons within easy reach of the thumb. 4. Test Across Devices: Test your buttons on various mobile devices to ensure they look and function correctly across different screen sizes and resolutions.