Preventing email typos on signup forms is a multifaceted endeavor, combining proactive validation, reactive cleaning, and user-friendly correction mechanisms. Key strategies encompass syntax checks, MX record verification, real-time validation tools (with caution regarding cost and false positives), typo suggestion, fuzzy matching algorithms, commercial validation services, double opt-in processes, bounce suppression, and A/B testing of signup forms. The effectiveness of certain validation services is debated, with some experts favoring clear form design and post-submission cleaning processes. A layered approach, blending technical validation with user experience considerations, appears optimal.