Structuring longer emails effectively is crucial for maintaining reader engagement. Start with a compelling subject line that clearly indicates the value of the email. Use a strong opening to hook the reader, followed by subheadings to break up the text and make it more scannable. Incorporate bullet points, numbered lists, and visual elements like images or infographics to enhance readability. End with a clear call-to-action (CTA) that directs the reader on what to do next.