Missing SPF records pose a significant security risk by leaving domains vulnerable to email spoofing, where malicious actors send emails with forged sender addresses to extract sensitive information from users. Detectify's research on the top 500 Alexa-ranked sites revealed that over 50% of these domains were susceptible due to either lack of or misconfigured email authentication, emphasizing the widespread nature of this issue. Email authentication protocols such as SPF, DKIM, and DMARC are crucial for preventing spoofed emails, but they require precise configuration, which is often complex and mishandled. The study found that only 42% of the top sites use DMARC, and among those relying only on SPF, 40% use a softfail setting, which is ineffective against spoofing. The guide underscores the importance of proper email server configuration to protect domains and highlights both the challenges faced by companies in implementing these measures and the steps necessary to improve email security.