Double opt-in confirmation links return NXDOMAIN in Estonia

Question

Hi,I use Klaviyo’s free plan with double opt-in. A customer reported that the confirmation link would not open. I reproduced the issue on two internet connections in Estonia: Elisa and Telia.The affected hostname is manage.kmail-lists.com. Chrome displays DNS_PROBE_FINISHED_NXDOMAIN.DNS tests from one affected connection:	Default DNS via the router: NXDOMAIN.			Google DNS (8.8.8.8): resolves successfully.			Cloudflare DNS (1.1.1.1): resolves successfully.	Both public resolvers return the CNAME manage.kmail-lists.com.cdn.cloudflare.net and IP addresses 172.64.146.244 and 104.18.41.12.The confirmation link works on mobile data. Switching Chrome’s Secure DNS provider to Google also made it open successfully.Customers affected by this issue cannot complete their subscription, leaving their profiles as “Never subscribed”.Separately, confirmation emails took approximately 5–10 minutes to arrive in my latest test, and over 10 minutes in an earlier test.Could a Klaviyo team member escalate this to the technical team to investigate the DNS issue and advise how to investigate the email delays? I’m on the free plan and cannot open a regular support ticket.Thank you.

berserk · Answer

Your testing already points at the cause. Google and Cloudflare resolve manage.kmail-lists.com fine while the Elisa and Telia resolvers say it doesn't exist, so the block is on the ISP side, usually a filter list or a cached bad answer. Nothing in your account can fix that.

What I'd do: email Elisa and Telia support with the hostname, the nslookup output from their resolver, and the 8.8.8.8 result side by side. Ask Klaviyo to contact them too, since they own the domain.

Meanwhile, Estonian signups can't confirm, so they stay Never subscribed. Where your consent setup allows it, switch that list to single opt in until the ISPs fix it. Adding a branded sending domain later? Send yourself a test and check whether the confirmation link host changes.

I work on email and DNS setups for brands, and resolver blocks like this come up more than you'd expect.

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