Summary
A strong consensus exists among email marketers, deliverability experts, and official documentation sources that sending marketing emails from a subdomain (rather than the parent domain) is highly recommended. The primary benefit is isolating the reputation of the main domain, protecting it from potential damage caused by marketing campaigns, such as deliverability issues, spam complaints, or the use of purchased lists. Using subdomains allows for segmentation of email traffic (e.g., separating marketing and transactional emails) and offers greater control over authentication and deliverability. It's crucial to properly authenticate each subdomain (SPF, DKIM, DMARC) and gradually warm up new subdomains or IP addresses to establish a positive sender reputation with ISPs.
Key findings
- Reputation Isolation: Subdomains protect the main domain's reputation from negative impacts associated with marketing emails.
- Traffic Segmentation: Subdomains enable segmentation of email traffic, separating marketing and transactional emails.
- Enhanced Control: Subdomains offer greater control over email authentication and deliverability management.
- Authentication Necessity: Proper authentication (SPF, DKIM, DMARC) is crucial for all subdomains to ensure deliverability.
- Warm-Up Importance: Gradual warm-up of new subdomains or IPs is essential for establishing a positive sender reputation.
Key considerations
- Authentication Setup: Ensure SPF, DKIM, and DMARC are correctly configured for each subdomain.
- Reputation Monitoring: Regularly monitor the reputation of subdomains to identify and address any deliverability issues.
- Gradual Ramp-Up: Increase sending volume gradually when starting with a new subdomain or IP address.
- IP strategy: Consider using dedicated IPs for higher volume sends.
- DMARC Policy Enforcement: Implement a DMARC policy to instruct email receivers on handling unauthenticated messages.
What email marketers say
11 marketer opinions
The prevailing recommendation from email marketers and deliverability experts is to send marketing emails from a subdomain rather than the parent domain. This practice isolates the reputation of the main domain, safeguarding it from any negative impact caused by marketing campaigns, such as deliverability issues or spam flags. Using subdomains allows for segmentation of email traffic, especially separating marketing and transactional emails. It also offers greater control and flexibility in managing email authentication and deliverability. Starting with a new subdomain or IP address necessitates a gradual warm-up process to establish a positive sender reputation with ISPs.
Key opinions
- Reputation Isolation: Using a subdomain protects the main domain's reputation from negative impacts of marketing campaigns.
- Segmentation: Subdomains allow for segmentation of email traffic, separating marketing and transactional emails.
- Control and Flexibility: Subdomains provide greater control over email authentication (SPF, DKIM, DMARC) and deliverability management.
- Ease of Delegation: Using a subdomain simplifies delegation of DNS settings to third-party senders.
- Warm-up Importance: Gradual warm-up of new subdomains or IPs is crucial for establishing a positive sender reputation.
Key considerations
- Authentication: Ensure proper authentication (SPF, DKIM, DMARC) is set up for the subdomain to ensure deliverability.
- IP Reputation: Monitor the reputation of the subdomain and associated IP addresses to identify and address any deliverability issues promptly.
- Gradual Ramp-up: When starting with a new subdomain or IP, gradually increase sending volume to avoid triggering spam filters.
- Traffic Monitoring: Implement systems to monitor traffic sent from subdomains.
- Consistent Content: Keep content consistent with agreed-upon guidelines to avoid triggering spam filters.
Marketer view
Email marketer from EmailOnAcid shares using a subdomain is a good idea, as it allows for more control and segmentation of your email traffic, ultimately safeguarding your main domain's reputation. Monitor your subdomains separately.
27 Jan 2025 - EmailOnAcid
Marketer view
Email marketer from Mailjet explains using a subdomain isolates your main domain's reputation, protecting it from marketing campaign issues. They advise setting up authentication (SPF, DKIM, DMARC) on the subdomain.
21 Dec 2023 - Mailjet
What the experts say
4 expert opinions
Experts consistently recommend using subdomains for marketing emails to isolate reputation and prevent deliverability issues from impacting critical transactional or corporate communications. Subdomains facilitate traffic segmentation and require independent authentication (SPF, DKIM, DMARC) to ensure proper deliverability.
Key opinions
- Reputation Isolation: Subdomains help maintain distinct domain reputations, preventing marketing-related deliverability problems from affecting transactional or corporate emails.
- Traffic Segmentation: Subdomains enable the separation of different types of email traffic, such as marketing and transactional.
Key considerations
- Independent Authentication: Each subdomain needs its own SPF, DKIM, and DMARC records configured for proper authentication and deliverability.
Expert view
Expert from Word to the Wise explains using a subdomain is beneficial for managing reputation, allowing you to isolate any deliverability issues stemming from marketing campaigns from your main domain.
29 Aug 2024 - Word to the Wise
Expert view
Expert from Email Geeks suggests using separate subdomains for marketing and transactional emails (e.g., email.mela.com and orders.mela.com) to maintain separate domain reputations and isolate deliverability issues.
28 Mar 2025 - Email Geeks
What the documentation says
5 technical articles
Email deliverability documentation consistently recommends using a separate domain or subdomain for bulk or marketing emails to protect the primary domain's reputation. Proper email authentication using SPF, DKIM, and DMARC is crucial for all sending domains and subdomains to ensure deliverability and prevent spoofing and phishing.
Key findings
- Reputation Protection: Using a separate domain/subdomain shields the primary domain's reputation from bulk email issues.
- Authentication is Key: Proper authentication (SPF, DKIM, DMARC) is vital for all sending domains, regardless of type.
- DMARC Enforcement: DMARC allows domain owners to specify how receivers handle unauthenticated emails, preventing spoofing.
- DKIM Verification: DKIM validates that emails originate from authorized servers and haven't been tampered with.
- SPF Authorization: Each subdomain needs its own SPF record to authorize sending servers.
Key considerations
- Authentication Configuration: Ensure SPF, DKIM, and DMARC are properly configured for the sending domain and any subdomains.
- DMARC Policy: Implement a DMARC policy to instruct email receivers on handling unauthenticated messages.
- Reputation Monitoring: Monitor domain and subdomain reputation to identify and address deliverability issues.
Technical article
Documentation from RFC shows that when sending emails using different subdomains, each subdomain needs its own SPF record defined to authorize the sending servers. This ensures deliverability and prevents spoofing.
26 Apr 2025 - RFC
Technical article
Documentation from DMARC.org explains that DMARC allows domain owners to specify how email receivers should handle messages that fail authentication checks (SPF and DKIM). This helps prevent email spoofing and phishing attacks.
1 Oct 2023 - DMARC.org
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