Domain & DNS-Level Checks

Does the port even exist? Before you send, you should check if a domain even has an MX record (a "harbor"). Sending to thousands of non-existent domains is a massive red flag to mailbox providers and a sign of a very poor list.

14 questions in this topic

What is a dead domain? What is a parked domain? What is a redirect domain? What is a restricted or blocked domain? What is a domain with missing MX records? How can you detect domains without active websites? What are NS and A record checks used for? How do SSL/TLS errors relate to domain health? What does a “no response” or “timeout” mean? What is a 200 vs 301 vs 404 domain response in hygiene terms? Why does HTTPS status matter for deliverability? What’s the difference between a suspended and expired domain? How do you classify redirect chains? What are CDN-redirected domains and why can they confuse validation tools?

Questions about Domain & DNS-Level Checks