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Knowledge Base & Operational DocumentationDomains, DNS & Business Email
Why Does Email From a Website Form Land in Spam After a Domain Change?
After a domain change, website-generated mail may use an unaligned sender or missing authentication records. Delivery can vary by recipient provider. What to check Inspect message headers, envelope sender, From domain, SPF and DKIM alignment, DMARC policy, and the site’s SMTP configuration. Check whether the new domain is authorized. Recommended next...
Why Does a Business Email Alias Stop Forwarding After a Mailbox Change?
An alias may depend on an old mailbox, group, transport rule, or forwarding address. Changing the destination account can leave the alias pointing to an inactive target. What to check Check alias and group membership, forwarding rules, mailbox status, delivery logs, and any loops or external forwarding restrictions. Recommended next step Update the...
Why Does a Website Subdomain Resolve but Show a Certificate Warning?
DNS can correctly point a subdomain to a server even when the certificate does not cover that hostname or the server presents a default certificate. What to check Check the exact hostname, certificate subject names, server binding, SNI, chain, redirect target, and whether a proxy terminates TLS elsewhere. Recommended next step Issue or bind a...
Why Does a Domain’s DNSSEC Validation Fail After a Nameserver Change?
Changing nameservers without coordinating DNSSEC records can leave the parent delegation pointing to a key that the new DNS provider does not use. Resolvers may then reject the domain. What to check Check DS records at the registrar or parent zone, DNSKEY records at the authoritative provider, rollover state, and resolver validation results....
Why Does a Domain’s Email Work Internally but Fail for External Senders?
Internal delivery may use local routing while external senders rely on public MX records and external mail filtering. The two paths can behave differently. What to check Check public MX answers, nameserver authority, mail gateway status, accepted domains, external SMTP responses, and recent DNS changes. Recommended next step Test from an external...
Why Does a Domain Work on One Resolver but Fail on Another?
Resolvers may hold different cached data, validate DNSSEC differently, or receive inconsistent answers from authoritative nameservers. What to check Compare authoritative responses, delegation, TTL, DNSSEC records, resolver validation status, and answers for A, AAAA, MX, or CNAME as relevant. Recommended next step Correct authoritative inconsistency...