What are CDN-redirected domains and why can they confuse validation tools?
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A CDN (Content Delivery Network) is a smart shortcut. Companies use it to serve their website faster by routing traffic through global servers. But here's the problem for email validators. A CDN sits in the middle and masks the real origin.
When a validator checks if a domain's active, it makes a request and gets a response from the CDN, not the actual website. The CDN's job is to serve content reliably. So it responds positively even if the underlying domain's been dead for years. It's like a mail forwarding service answering for a closed business. The mailbox doesn't exist anymore, but the forwarding service is still accepting letters and claiming everything's fine.
This creates false positives. An address might show "valid" even though the business behind it shut down years ago. Popular CDNs like Cloudflare also block certain types of requests they consider bot traffic, which can return misleading "Unknown" results. If you're working with international or security-conscious contacts, this difference in responses matters. Contact our SOS Hotline if you're seeing unexplained validation results on specific domains.
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