Email marketers have access to a wide array of tools to combat spam and enhance deliverability, encompassing both free and paid options. Free tools like Mail-tester, Inboxbooster.com, Warmy, Senderok, and Mailjet's free plan provide content analysis, spam score assessment, and basic deliverability testing. Setting up seed accounts with various providers (Gmail, Yahoo, Hotmail) is another common free method for monitoring inbox placement. For more comprehensive solutions, paid services such as Litmus, GlockApps, Everest Validity, Zerobounce, and Email Hippo offer features like inbox placement testing, reputation monitoring, DMARC analysis, email validation, and detailed analytics. Documentation from Spamhaus, DKIM Validator, MXToolbox, and Google Postmaster Tools provide insights into IP blacklisting, DKIM validation, DNS record checks, and sender reputation management, all vital for understanding and mitigating deliverability issues. Experts caution that the effectiveness of AI-driven tools can diminish over time due to adaptive learning and that there is no perfect way to check inbox placement. A holistic approach including authentication checks, list hygiene, feedback loops, and careful selection of independent third-party authentication services is recommended.