Validating email addresses involves a multi-faceted approach, considering both syntax and deliverability. Experts and documentation sources agree that modern email syntax is complex, allowing for special and internationalized characters (Unicode). While regular expressions can check syntax, overly strict patterns are discouraged as they may reject valid addresses. A more reliable approach involves deliverability checks, such as sending confirmation emails and monitoring bounces. Email validation services offer comprehensive checks, including syntax, domain existence, mailbox existence, and spam trap detection. Marketers also highlight the importance of typo detection, plus addressing, and detecting disposable email addresses to maintain list quality and sender reputation.