Summary
Setting up email subdomains is a fundamental strategy for optimizing email deliverability and managing sender reputation. It involves configuring specific DNS records for the chosen subdomain, which can be distinct from the main domain's records. This approach is highly recommended for segmenting different types of email traffic, such as marketing versus transactional emails, thereby protecting the overall brand reputation. The exact setup process often depends on your web-hosting provider, like cPanel, or your email service provider, but the core requirement remains the correct configuration of DNS records.
Key findings
- Reputation Segmentation: Using subdomains allows for reputation segmentation, enabling email marketers to separate different email streams-for example, marketing emails from transactional ones. This practice helps isolate and protect the main domain's reputation, as each subdomain develops its own distinct sending reputation.
- Essential Authentication Records: The most crucial DNS records required for a sending subdomain are SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance). These are typically configured as TXT records and are vital for email authentication, helping receiving servers verify the sender's legitimacy and prevent spoofing.
- Required DNS Record Types: Beyond SPF, DKIM, and DMARC, subdomains often require MX records to direct inbound mail traffic, and CNAME records for domain verification, tracking, and custom return paths. An A record, however, is generally not needed for the purpose of sending emails from a subdomain.
Key considerations
- Provider-Specific Setup: The practical steps for setting up subdomains and their associated DNS records can vary significantly based on your web-hosting provider, such as cPanel, or your specific email service provider (ESP). It is important to consult their documentation for precise instructions on adding subdomains and managing DNS entries.
- Dedicated DNS Records: Each subdomain used for email sending requires its own dedicated set of DNS records, including SPF, DKIM, and DMARC, which should be configured to align with the subdomain's specific sending practices and authorized senders. These records are distinct from those of the parent domain.
- Comprehensive Configuration: To ensure optimal deliverability and proper email functionality, it is essential to correctly configure all necessary DNS records-including MX records for mail routing, TXT records for SPF, DKIM, and DMARC, and CNAME records for tracking and return-path. Misconfigurations can lead to deliverability issues.
What email marketers say
12 marketer opinions
Setting up email subdomains is a strategic move for advanced email deliverability, allowing marketers to segment their sending reputation and protect their primary domain. This process involves configuring specific DNS records for the chosen subdomain, which are distinct from those of the main domain. While the exact setup depends on the web hosting provider or email service, the core requirement is the precise configuration of essential DNS records to ensure proper email authentication and routing. This best practice helps maintain high deliverability rates across various email campaigns.
Key opinions
- Reputation Management: Deploying subdomains is a best practice for isolating email sending reputation, effectively separating different types of email traffic, like marketing or transactional messages, to safeguard the main domain's standing.
- Authentication Essentials: For reliable email deliverability, each sending subdomain requires dedicated SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance) DNS records. These TXT records are critical for recipient server verification.
- Core DNS Requirements: Beyond authentication records, subdomains used for email must have correct MX (Mail Exchanger) records for mail routing, and often CNAME records for tracking and verification. Notably, an A record is generally not required for the sole purpose of sending emails from a subdomain.
Key considerations
- Platform-Specific Setup: The precise steps for configuring a subdomain and its DNS records can vary significantly based on your web hosting provider, such as cPanel, or your specific email service provider. Always refer to their documentation for accurate guidance.
- Dedicated Record Configuration: Each subdomain designated for email sending needs its own comprehensive set of DNS records, including SPF, DKIM, and DMARC, ensuring they are specifically tailored to the subdomain's sending practices and authorized sources. These must be distinct from the parent domain's records.
- Thorough Record Implementation: To achieve optimal email functionality and prevent deliverability issues, it is imperative to correctly implement all required DNS entries. This includes MX records for mail exchange, TXT records for authentication (SPF, DKIM, DMARC), and CNAME records for features like tracking.
Marketer view
Marketer from Email Geeks explains that setting up subdomains depends on your web-hosting provider and their software, noting that with cPanel it's typically easy to add a subdomain and manage its records.
12 Jun 2025 - Email Geeks
Marketer view
Marketer from Email Geeks clarifies that an A record is not necessary for sending emails from a subdomain and that crucial records include TXT for SPF, MX, TXT for DKIM, potentially TXT for DMARC (if not on the organizational domain), and other records like A for tracking or TXT for Google Postmaster Tools.
28 Jun 2024 - Email Geeks
What the experts say
2 expert opinions
Setting up email subdomains is a key strategy for optimizing deliverability and managing sender reputation by segmenting different email traffic types, such as marketing versus transactional messages. Each subdomain establishes its own distinct reputation and therefore requires its own specific authentication records. It is crucial to configure dedicated SPF, DKIM, and DMARC records for every sending subdomain, which must be published as TEXT records in the DNS, separate from the parent domain's configurations. These records are fundamental for verifying sender legitimacy, ensuring message integrity, and dictating how receiving servers handle unauthenticated mail.
Key opinions
- Traffic Segmentation: Setting up email subdomains offers a clear benefit for segmenting email traffic, allowing distinct separation of messages, such as marketing campaigns from transactional notifications.
- Individual Reputation: Each subdomain used for sending email develops and maintains its own sender reputation, independent of the main domain or other subdomains.
- Core Authentication Records: Essential DNS records for email authentication on any domain or subdomain include SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance).
- Record Functions: SPF records authorize sending IP addresses, DKIM uses cryptographic signatures to ensure message integrity, and DMARC defines policies for how email receivers should handle authentication failures.
Key considerations
- Dedicated Authentication: Each email subdomain requires its own unique set of authentication records, including SPF, DKIM, and DMARC, configured distinctly from the parent domain's settings.
- DNS Record Type: All essential email authentication records-SPF, DKIM, and DMARC-must be published as TEXT records within the DNS for the specific subdomain.
- Reputation Protection: Utilizing subdomains for different email types helps protect your overall sender reputation, as issues with one stream are less likely to impact the others due to their separate reputations.
Expert view
Expert from Word to the Wise explains that setting up email subdomains is beneficial for segmenting email traffic, such as separating marketing from transactional emails, to manage and protect sender reputation. Each subdomain develops its own reputation and requires its own specific authentication records like SPF, DKIM, and DMARC, distinct from the parent domain's records.
11 Jun 2022 - Word to the Wise
Expert view
Expert from Word to the Wise details the essential DNS records required for email authentication, which are crucial for any domain or subdomain sending email. These include SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance). SPF records specify authorized sending IP addresses, DKIM uses cryptographic signatures for message integrity, and DMARC defines policies for handling authentication failures, all of which are published as TEXT records in DNS.
6 May 2023 - Word to the Wise
What the documentation says
5 technical articles
To effectively set up email subdomains and ensure optimal deliverability, a precise configuration of specific DNS records is essential. These typically include SPF and DKIM records, published as TXT records for robust email authentication. MX records are crucial for proper mail routing, particularly when using services like Google Workspace or Microsoft 365. Additionally, CNAME records are widely required for purposes such as domain verification, tracking email engagement, and establishing custom return paths for bounce handling. While the exact setup and required values may vary slightly depending on the email service provider or platform, these core DNS types are universally needed to validate sending authority and protect against email spoofing.
Key findings
- Universal Authentication: SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) TXT records are consistently required across all providers for sender authentication, vital for preventing spoofing and ensuring message integrity for your subdomain.
- Mail Routing and Tracking: MX records are essential for directing inbound email traffic to the correct mail servers for subdomains, while CNAME records facilitate domain verification, email tracking, and custom return paths for efficient bounce handling.
- Provider-Specific CNAMEs: Different email service providers, such as SendGrid, Mailgun, and Postmark, detail specific CNAME records necessary for their unique domain verification, tracking, and custom return path functionalities, which must be added to your subdomain's DNS.
Key considerations
- Comprehensive DNS Setup: Setting up a sending subdomain requires a thorough configuration of multiple DNS record types, including SPF, DKIM, MX, and CNAME, to ensure full email functionality and deliverability.
- Align with Provider Docs: Always refer to the specific documentation from your chosen email service provider-be it SendGrid, Mailgun, Postmark, Google Workspace, or Microsoft 365-as their precise DNS record values and setup steps will differ.
- Purpose-Driven Records: Each type of DNS record serves a distinct purpose, from authentication (SPF, DKIM) and mail routing (MX) to feature enablement like tracking, custom return-path, and bounce handling (CNAME).
Technical article
Documentation from SendGrid Docs explains that setting up domain authentication for a sending domain, which can be a subdomain, is crucial for deliverability and requires specific CNAME records for verification and return path, along with SPF and DKIM records for authentication.
24 Sep 2024 - SendGrid Docs
Technical article
Documentation from Mailgun Help Center details the necessary DNS records for a sending domain, including subdomains, which involve MX records for inbound mail, CNAME records for domain verification and tracking, and TXT records for SPF and DKIM for email authentication.
3 Mar 2023 - Mailgun Help Center
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