CampaignKit

CampaignKit's official email validation server provides real-time and batch email verification through five specialized tools covering single email validation, asynchronous batch processing for large lists, job status monitoring, paginated results retrieval, and account statistics tracking. The implementation uses Server-Sent Events over HTTPS for transport with JSON-RPC 2.0 messaging, enabling validation checks for email format, deliverability, disposable/temporary domains, catch-all addresses, and domain verification. Built for marketers and developers who need to reduce bounce rates and protect sender reputation, it operates on a credits-based model where users only pay for successfully validated emails.