Selecting the best blocklist monitoring service hinges on several factors: cost, customization, timeliness, and relevance. Postmastery offers high customization, while Hetrix provides budget-friendly options. MXToolbox and BlacklistAlert offer customizable alerts and detailed reports. Experts recommend focusing on relevant RBLs, understanding why you were listed, and having a process to address and prevent recurrence. Combining free and paid tools can be cost-effective. Spamhaus provides real-time data, MultiRBL offers fast lookups, and GlockApps integrates blocklist monitoring into deliverability testing. The necessity of fast notifications and reputable tools to avoid false positives is underscored.