RBL Checker

RBL Checker queries DNS-based blacklists for a provided IP address or domain to determine listing status. Target users include mail administrators, security engineers, and IT operations teams responsible for outbound email deliverability and sender reputation. It is used during initial mail infrastructure setup, during investigations of sudden bounce rates, after receiving a listing alert, or as part of ongoing reputation monitoring. The tool focuses on data accuracy, speed, and clear per-provider results to support remediation decisions.\n\nConceptually the tool performs per-provider DNS lookups. For an IP input, it reverses the IPv4 octets and queries the provider’s DNSBL domain (for example reverse_ip.in-addr.arpa.dnsbl). For a domain, it resolves the domain to its A records and runs the same lookup for each address. Queries use standard DNS protocols and return textual or numeric responses defined by each provider. The results are normalized into a common schema to facilitate automation and human review.\n\nCore features include multi-provider lookups, optional provider selection, configurable timeouts, and optional caching. Outputs provide is_listed, per-provider status, and a remediation_suggestion field that points to common next actions such as requesting delisting or reviewing mail practices. Advanced users can enable severity scoring, historical comparisons, and integration hooks for alerting systems.\n\nUse cases span pre-delivery checks before campaigns, monitoring on onboarding, and post-incident investigations after a listing appears. It benefits mailbox admins, security teams, and operations staff by reducing guesswork and speeding response. Unique value lies in combining multiple DNSBL sources with structured, machine-readable results and optional remediation guidance, all while preserving input privacy and avoiding dependence on any single provider.