Summary
Emails frequently fail to deliver after switching DNS nameservers, even when MX records are intended to remain the same, due to a combination of DNS propagation delays, caching issues, and crucially, the improper transfer or configuration of essential DNS records. Receiving mail servers may continue to query old, cached nameservers or, upon querying the new ones, find missing or incorrect DNS information necessary for email routing and authentication. Records like SPF, DKIM, and DMARC are particularly vital for validating email legitimacy, and their absence or misconfiguration on the new nameservers often leads to messages being rejected or flagged as suspicious by recipient systems.
Key findings
- DNS Propagation and Caching Delays: Even if MX records are conceptually unchanged, internet service providers and mail servers across the globe need time to update their caches and query the new nameservers. During this propagation period, old, cached DNS information can cause emails to fail delivery.
- Missing or Incorrect DNS Records: The most common issue is that critical email-related DNS records-specifically MX, SPF, DKIM, and DMARC-are not correctly transferred or configured on the new nameservers. Without these, recipient mail servers cannot properly route messages or will reject them due to failed authentication checks.
- No Automatic DNS Record Transfer: DNS records are not automatically migrated when nameservers are switched. They must be manually duplicated to the new DNS hosting environment, a step often overlooked, leading to an incomplete or incorrect DNS zone on the new servers.
- DNSSEC Incompatibility: In some instances, switching to nameservers that do not support DNSSEC, when a domain was previously configured for it, can cause email delivery failures by breaking trust chains for DNS validation.
Key considerations
- Comprehensive DNS Record Migration: Ensure all critical DNS records related to email, including MX, SPF, DKIM, and DMARC, are accurately and completely copied from your old DNS configuration to your new nameservers. These records are not automatically transferred and are essential for email routing and authentication.
- Account for DNS Propagation: Be aware that DNS changes require time to propagate across the internet. During this period, which can range from a few hours to 48-72 hours depending on TTL settings, some mail servers may still query old DNS information, leading to intermittent delivery issues. Patience is key.
- Verify DNSSEC Compatibility: If your domain previously utilized DNSSEC, confirm that your new nameservers support it and that your domain's DNSSEC configuration is updated correctly. Incompatibility can be a hidden cause of delivery problems.
- Proactive DNS Verification: Before and after the nameserver switch, use DNS lookup tools to confirm that all necessary email records are correctly published and resolving on the new nameservers. This proactive check can help identify and rectify issues quickly.
What email marketers say
9 marketer opinions
When DNS nameservers are changed, even if MX records are intended to remain constant, email delivery often fails. This is primarily because mail systems critically depend on comprehensive and accurate DNS information for routing and authentication. New nameservers must be meticulously populated with all existing DNS records, including MX, SPF, DKIM, and DMARC. If these records are incomplete, incorrect, or missing, recipient mail servers will be unable to locate the correct mail destination or will reject messages due to failed authentication checks, perceiving them as suspicious or unauthorized, irrespective of MX record status. Furthermore, an unexpected incompatibility with DNSSEC can also disrupt mail flow.
Key opinions
- Authentication Record Oversight: A common cause of delivery failure is the omission or misconfiguration of essential email authentication records, such as SPF, DKIM, and DMARC, when transitioning to new nameservers. Even if MX records are correctly moved, the absence of these crucial TXT records leads to recipient mail servers rejecting or flagging emails.
- Incomplete DNS Zone Transfer: DNS records are not automatically transferred during a nameserver switch. All necessary records, including A, MX, and various TXT records for authentication, must be manually duplicated to the new DNS host's zone file; an incomplete transfer will prevent proper email routing and validation.
- Impact of DNSSEC Discrepancy: If a domain was previously configured with DNSSEC and the new nameservers do not support it, or if the DNSSEC setup is not correctly updated, this can break trust chains for DNS validation, leading to email delivery problems.
- Reliance on Comprehensive DNS: Mail servers rely on the entirety of a domain's DNS records, not just MX, to route and validate emails. A change in nameservers requires that the new DNS environment mirrors the complete, accurate set of all relevant email-related records to ensure uninterrupted service.
Key considerations
- Meticulous DNS Record Duplication: Ensure that every critical DNS record associated with email-including MX, SPF, DKIM, and DMARC-is precisely copied and correctly configured on the new nameservers. Do not assume automatic transfer, as these records are vital for proper routing and authentication.
- Pre- and Post-Migration Verification: Before initiating the nameserver switch, meticulously document all existing DNS records. After the change, use reliable DNS lookup tools to verify that all records have propagated correctly from the new nameservers, addressing any discrepancies promptly.
- Review DNSSEC Requirements: If your domain uses DNSSEC, confirm that your new DNS provider fully supports it and that the DNSSEC configuration is accurately migrated and validated to avoid authentication failures that could impede email delivery.
- Anticipate Propagation Delays: Be prepared for potential, albeit temporary, email delivery issues as DNS changes propagate across the internet. This period can last up to 48-72 hours, during which some mail servers may still query outdated information, causing intermittent problems.
Marketer view
Email marketer from Email Geeks identified the root cause of his email delivery issue after nameserver changes as moving to nameservers that do not support DNSSEC, while the domain was previously configured for it.
31 Oct 2024 - Email Geeks
Marketer view
Email marketer from Reddit (r/sysadmin) shares that emails often fail after nameserver changes because, even if MX records aren't intended to change, they might not be correctly transferred to the new nameservers, or default to an empty set. It also highlights the importance of checking SPF and DKIM records, as these can be missed during the migration.
15 Nov 2024 - Reddit (r/sysadmin)
What the experts say
2 expert opinions
Email delivery failures after switching DNS nameservers, even without MX record changes, are primarily caused by the inherent time required for DNS propagation and caching. Mail servers may continue to query old, cached nameservers, or, once directed to the new nameservers, might fail to find the necessary MX records if the new DNS hosting environment is not fully propagated or correctly serving the domain's records. This delay in global DNS updates, influenced by Time To Live (TTL) settings and the hierarchical nature of DNS, can lead to lookup failures and bounced emails.
Key opinions
- DNS Propagation Delays: The internet's DNS resolvers need time to learn and update to the new authoritative nameservers. During this propagation period, mail servers may attempt to query outdated information, leading to failed MX record lookups.
- Stale DNS Caching: Recipient mail servers and local DNS resolvers cache previous nameserver information. Until these caches expire and refresh, they may attempt to query the old nameservers, resulting in an inability to find the current MX record.
- New Nameserver Configuration: Even if MX record values are conceptually unchanged, the new nameservers must be fully configured and actively serving the domain's complete DNS zone, including MX records, for successful mail routing and delivery.
- Root Server Update Importance: A crucial, often overlooked, step is ensuring that the global root nameservers correctly return your new nameservers. If this delegation is not updated or is incorrect, it impedes the discovery of your domain's DNS information.
Key considerations
- Allow for DNS Propagation: Understand that DNS changes, particularly nameserver switches, require time to propagate across the internet. Plan for a period of potential intermittent email delivery as DNS resolvers update their caches, a process that can take 24-72 hours.
- Confirm New Nameserver Readiness: Before and after the switch, verify that your new nameservers are correctly configured to serve all necessary domain records, including your existing MX records. The new host must be actively and accurately resolving your domain's DNS.
- Verify Registrar Delegation: Ensure your domain registrar's settings are updated to correctly point to the new nameservers. Incorrect delegation at this fundamental level will prevent global DNS from locating your new authoritative servers.
- Monitor DNS Resolution Post-Switch: Actively use DNS lookup tools (such as dig, nslookup, or online DNS checkers) from various geographic locations to confirm that your MX records are consistently resolving from the new nameservers globally, indicating successful propagation.
Expert view
Expert from Email Geeks explains that receiving servers might be using old, cached nameservers, leading to an inability to find the MX record and subsequently rejecting mail. She also suggests ensuring the root nameservers are correctly returning the new nameservers, noting that changing nameservers often requires extra steps.
28 May 2022 - Email Geeks
Expert view
Expert from Word to the Wise explains that email delivery failures after switching DNS nameservers, even when MX record values are intended to remain unchanged, occur because the internet's DNS resolvers need time to propagate and learn the new authoritative nameservers. If these new nameservers do not correctly host the domain's MX records, or if DNS propagation (influenced by DNS caching and TTL-Time To Live) has not completed, mail servers will attempt to query the new, potentially unconfigured, nameservers for MX records, leading to lookup failures and bounced emails.
16 May 2023 - Word to the Wise
What the documentation says
7 technical articles
Even when the intention is to retain existing MX records, email delivery can falter after a DNS nameserver transition because the newly configured nameservers might not accurately host all necessary DNS information, particularly crucial authentication records like SPF, DKIM, and DMARC. These records, vital for validating email legitimacy, are often overlooked or incorrectly configured during the transfer. Coupled with the time required for DNS changes to propagate globally and for internet-wide caches to refresh, recipient mail servers may continue to query outdated information or, upon reaching the new nameservers, reject messages due to missing or invalid authentication, regardless of the MX record's perceived consistency.
Key findings
- Incomplete Record Migration: The new nameservers frequently lack a complete and accurate set of all necessary DNS records for email, including not just MX, but critically, SPF, DKIM, and DMARC.
- Overlooked Authentication Records: SPF, DKIM, and DMARC records are often forgotten or improperly configured during a nameserver switch, which are essential for email authentication and preventing messages from being rejected as spam.
- Persistent DNS Caching: Mail servers and DNS resolvers across the internet cache old nameserver information. Until these caches expire, they may attempt to query the old, now inactive, nameservers, causing delivery failures.
- Manual Configuration Requirement: DNS records do not automatically transfer with a nameserver switch; they must be manually duplicated and meticulously configured on the new DNS hosting environment.
Key considerations
- Meticulous Record Duplication: Ensure all critical DNS records for email-including MX, SPF, DKIM, and DMARC-are precisely copied and correctly configured on the new nameservers, as these are vital for routing and authentication.
- Anticipate Propagation Delays: Be prepared for potential, temporary email delivery issues as DNS changes propagate across the internet; this period can last up to 48-72 hours, during which some mail servers may still query outdated information.
- Verify Comprehensive DNS Setup: After the switch, use reliable DNS lookup tools to confirm that all necessary email-related records are correctly published and resolving from the new nameservers, not just MX records.
- Prioritize Authentication Records: Pay particular attention to the accurate setup and validation of SPF, DKIM, and DMARC records on the new nameservers, as their absence or misconfiguration is a leading cause of delivery failures.
Technical article
Documentation from Cloudflare explains that emails may fail to deliver after switching nameservers due to the new nameservers not having the correct DNS records, including MX, SPF, DKIM, and DMARC. It emphasizes ensuring all necessary email-related DNS records are accurately configured on the new nameservers, as well as accounting for DNS propagation time.
15 Sep 2021 - Cloudflare Developers
Technical article
Documentation from Hostinger explains that emails might fail after nameserver changes due to two main reasons: DNS propagation time, where the new nameservers need time to update globally, and incorrect DNS records, including MX, SPF, and DKIM, on the new nameservers. It stresses the importance of ensuring all necessary records are manually added to the new DNS zone.
13 Feb 2025 - Hostinger Tutorials
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