What are the implications of using sequential CNAMEs for email FROM domains and the ethical concerns with Cloudflare?
Michael Ko
Co-founder & CEO, Suped
Published 19 Apr 2025
Updated 19 Aug 2025
8 min read
When configuring email sending infrastructure, CNAME records are often used for various purposes, but their sequential application, particularly for email FROM domains, can introduce layers of complexity and potential issues for deliverability. This practice involves chaining multiple CNAMEs, where one CNAME points to another, eventually resolving to the final A or MX records necessary for email to function.
The concern intensifies when services like Cloudflare are part of this chain. While CNAME records are legitimate DNS entries, excessive indirection can lead to performance degradation during DNS resolution. More importantly for email, it can complicate authentication processes, making it harder for receiving mail servers to validate sender authenticity.
Beyond technical challenges, the choice of DNS provider, particularly Cloudflare, also brings ethical considerations to the forefront. These concerns, while not directly impacting DNS resolution speed or authentication, can influence the broader perception and operational approach of those interacting with your domain. Understanding these implications is crucial for maintaining optimal email deliverability and upholding brand reputation.
Understanding CName chains and email deliverability
A CNAME record, or Canonical Name record, functions as an alias for another domain name. When a domain uses a CNAME for its email FROM address, the mail server must resolve this alias to find the actual IP address and other relevant DNS records. In a sequential CNAME setup, this process involves multiple lookups, creating a chain of redirections before the authoritative records are found.
While DNS resolvers are generally efficient, adding multiple CNAMEs into a chain can introduce minor latency. This isn't usually a major issue for web traffic, but for email, particularly during authentication checks, it adds steps. Each CNAME in the chain needs to be resolved before the next step, such as an SPF lookup or DKIM verification, can occur.
For example, if your email FROM domain is custom.domain.com, and it CNAMEs to install.domain.com, which then CNAMEs to domain.cloudflare.net, the receiving server performs three lookups just to find the final authoritative records. While a chain of two to four CNAMEs is generally considered acceptable, some email systems might view excessive indirection with suspicion, potentially impacting your domain reputation. Maintaining fewer CNAMEs simplifies DNS management.
CName records and email authentication mechanisms
The primary concern with CNAMEs for email FROM domains relates to email authentication protocols like SPF, DKIM, and DMARC. These protocols rely heavily on direct DNS lookups to verify the sender's legitimacy. A key rule to remember is that a CNAME record cannot coexist with other record types for the same hostname, such as MX, TXT (for SPF or DKIM), or A records, at the root level of a domain.
For SPF, while CNAMEs themselves don't count towards the 10-lookup limit, the DNS queries for SPF mechanisms (like include or a terms) that follow the CNAME chain will. This can inadvertently push you over the limit if your SPF record is already complex, leading to SPF TempError failures and impacting deliverability. For DKIM, if CNAMEs are used, they must point directly to the DKIM key and not be proxied by services like Cloudflare's proxy, which can interfere with the signature verification.
CNAME for web hosting
Purpose: Commonly used to alias a subdomain (e.g., www.yourdomain.com) to a root domain or a hosting provider's URL.
Impact on performance: Minimal, as web browsers typically cache DNS lookups.
Coexistence: Generally permissible to have other records (like MX) at the root domain while CNAMEs exist for subdomains.
CNAME for email FROM domains
Purpose: Used to alias the sending domain (often for tracking or branding) to an email service provider's domain.
Impact on performance: Can cause delays in email authentication, potentially affecting deliverability.
Coexistence: A CNAME cannot coexist with other DNS records (e.g., MX, SPF, DKIM) for the exact same hostname. This is a critical point that often breaks email functionality.
I've often seen confusion arise when setting up CNAME delegation for SPF and DKIM. If a domain has a CNAME at the root (apex domain), it cannot have other records like MX or TXT for email authentication. This is a fundamental DNS limitation that can cause significant email deliverability problems, leading to emails failing SPF or DKIM checks and ending up in spam folders or being rejected outright. Always ensure that email-related DNS records are configured directly on the domain or a dedicated subdomain without conflicting CNAMEs at the same level.
Cloudflare's role and potential impact on deliverability
Cloudflare is a widely used content delivery network (CDN) and DNS provider. They offer a feature called "CNAME flattening" or "CNAME at the root," which allows apex domains to behave like CNAMEs, resolving to A records dynamically. While this is beneficial for web traffic, its interaction with email DNS records is often misunderstood.
When using Cloudflare for your domain, it's crucial to ensure that your mail-related DNS records (MX, SPF, DKIM) are set to "DNS only" (gray cloud icon) rather than "Proxied" (orange cloud icon). If proxied, Cloudflare acts as an intermediary, obscuring the direct IP address of your mail server, which can break SPF and DKIM authentication. Many mail servers will fail to deliver messages if they cannot directly verify the sender's domain via its public DNS records.
Using cloudflare for email DNS
Misconfiguration risk: Incorrectly proxying MX, SPF, or DKIM records through Cloudflare's network can lead to authentication failures.
SPF & DKIM: Proxying can interfere with direct DNS lookups required for SPF and DKIM verification.
While Cloudflare can be a robust DNS provider, it requires careful configuration for email, and any attempt to use their proxy for email DNS records will likely lead to deliverability issues. It's often safer to manage email-specific DNS records directly or via a dedicated email service provider's instructions, ensuring they are not proxied through Cloudflare's CDN.
Ethical concerns when using Cloudflare
Beyond the technical aspects, the choice to use Cloudflare can raise ethical questions for some. There have been criticisms regarding Cloudflare's policy of not taking action against websites hosting hate speech, child abuse material, or other illicit content, even when complaints are filed. A notable example is their past protection of websites associated with hate groups, as reported by ProPublica. Their argument centers on not being the arbiter of content, which some view as providing a safe haven for harmful online activity.
Another area of concern is their network architecture, which involves breaking TLS (Transport Layer Security) encryption to inspect traffic for security purposes. While this is a common practice for CDNs, it means that Cloudflare has the technical ability to sniff or intercept traffic, raising privacy concerns for some users and organizations. This raises questions about data privacy and the extent to which a service provider should have access to or control over encrypted communications.
Ethical concerns summary
Content neutrality policy: Their stance on not policing content means they may host sites many find objectionable, potentially leading to association issues.
TLS interception: While for security, it inherently allows them to access unencrypted traffic, raising privacy questions.
Origin of funding: Some criticisms point to the company's roots being tied to organizations accused of extortionary practices against email marketers.
Best practices and alternative approaches
To mitigate potential issues with sequential CNAMEs for email FROM domains, the best practice is to minimize their use or avoid them altogether for critical email authentication records. If you must use CNAMEs, ensure that the final record type resolves correctly for email, particularly for MX, SPF, and DKIM.
For Cloudflare users, always set your email-related DNS records to "DNS only" to prevent any interference from their proxy. This direct approach ensures that mail servers can perform necessary authentication checks without additional layers of resolution, which can often be misconfigured. Proper configuration of SPF, DKIM, and DMARC directly on your domain's DNS is fundamental for strong email deliverability.
While sequential CNAMEs might technically work for web traffic, the intricacies of email authentication make them a less reliable choice for FROM domains. Simpler DNS configurations generally lead to fewer deliverability issues and easier troubleshooting. Prioritizing direct DNS entries for email authentication helps maintain a robust sending reputation and ensures your messages reach the inbox.
Example of direct DNS records for emailDNS
yourdomain.com. IN MX 10 mail.yourdomain.com.
yourdomain.com. IN TXT "v=spf1 include:_spf.yourdomain.com ~all"
dkim._domainkey.yourdomain.com. IN CNAME dkim.provider.com.
Views from the trenches
Best practices
Ensure CNAMEs for email (like DKIM) are not proxied through CDNs and are set to DNS only.
Minimize CNAME chains for email FROM domains to reduce DNS resolution complexity.
Regularly monitor your DNS records to ensure they resolve correctly and do not conflict.
Common pitfalls
Using proxied CNAMEs for MX or SPF records, which can break email authentication.
Creating deeply nested CNAME chains that can cause lookup timeouts for some mail servers.
Ignoring the SPF 10-lookup limit, which CNAME-resolved includes can indirectly contribute to.
Expert tips
For optimal deliverability, directly configure A/MX/TXT records where possible instead of relying on CNAME chains.
Utilize subdomains for CNAMEs (e.g., `sends.yourdomain.com`) to avoid conflicts with your root domain's email records.
Consider the ethical stance of your service providers as it can indirectly affect your brand perception.
Expert view
Expert from Email Geeks says that while CNAMEs don't directly count towards SPF query limits, the subsequent lookups they trigger do count, which is an important distinction to remember.
September 3, 2019 - Email Geeks
Marketer view
Marketer from Email Geeks says that they are looking for a solution that works for all clients regardless of their Cloudflare usage, and a two-CNAME setup might be a way to cover that scenario.
September 3, 2019 - Email Geeks
Final thoughts on CName records and ethical considerations
Navigating the complexities of sequential CNAMEs for email FROM domains requires a clear understanding of DNS limitations and email authentication protocols. While technically feasible for web, applying deep CNAME chains to email sending domains can introduce unnecessary hurdles for deliverability, particularly when factoring in SPF lookup limits and DKIM verification.
Furthermore, the choice of a DNS provider, such as Cloudflare, comes with its own set of technical considerations for email and broader ethical implications. While these ethical concerns might not directly cause emails to bounce, they reflect on a company's values and can influence professional relationships within the industry. Prioritizing direct DNS configurations for email authentication and being aware of the ethical stance of your infrastructure partners contributes to a healthier and more reliable email ecosystem.
Cloudflare are part of this chain. While CNAME records are legitimate DNS entries, excessive indirection can lead to performance degradation during DNS resolution. More importantly for email, it can complicate authentication processes, making it harder for receiving mail servers to validate sender authenticity.
