During device testing, you may encounter several common issues: - Rendering Issues: Emails may not appear the same on different devices due to varying support for HTML and CSS. - Broken Links and Images: Links and images may not display correctly if they are not optimized for all devices. - Font and Text Problems: Fonts may not render correctly, and text may appear too small or too large on certain devices. - Interactive Elements: Buttons and interactive elements may not function as intended on all platforms.