Summary
The consensus leans heavily towards using a subdomain, especially for marketing or high-volume emails, to protect the primary domain's reputation and deliverability. While technically feasible to use the primary domain if authentication (SPF, DKIM, DMARC) is properly configured and the client understands the implications, subdomains offer better isolation, control, and testing capabilities. Crucially, a proper return-path subdomain is vital for DMARC alignment. Brand consistency and potential dilution of brand perception are important considerations. Clear communication with the client regarding their goals and shared reputation risks is essential.
Key findings
- Reputation Protection: Subdomains protect the primary domain's reputation and deliverability.
- Control & Isolation: Subdomains offer better control over sender reputation and isolate email streams.
- DMARC Alignment: A subdomain for the return-path is critical for DMARC alignment.
- Testing Advantage: Subdomains allow for safer testing of new email programs and vendors.
- Authentication Key: Proper SPF, DKIM, and DMARC authentication are crucial regardless of domain choice.
Key considerations
- Client Goals: Understand the client's goals and desired 'From' address display.
- Shared Reputation Risks: Assess the risks of sharing reputation with other email streams from the primary domain.
- Branding Consistency: Maintain consistent branding across subdomains to avoid diluting brand perception.
- Authorized Branding: Avoid using unauthorized brand names in subdomains to prevent filtering issues.
- Volume: High email volume is a strong indicator a sub-domain is needed.
What email marketers say
10 marketer opinions
The provided responses overwhelmingly suggest that using a subdomain for email sending, especially for marketing or cold outreach, is a best practice. The primary reason is to isolate and protect the reputation of the main domain. A subdomain allows for better management and control over sender reputation, preventing deliverability issues from impacting business-critical communications. However, considerations around consistent branding and potential dilution of brand perception need to be carefully managed.
Key opinions
- Reputation Isolation: Using a subdomain isolates your email marketing reputation from your primary domain.
- Reputation Management: A subdomain allows for managing and protecting sender reputation separately.
- Deliverability Protection: Using a subdomain prevents deliverability issues from impacting business-critical emails.
- Brand Authentication: Subdomain setup and authentication help verify sender legitimacy with email providers.
- Strategic Long-Term: Subdomains allow you to establish, monitor, and maintain a healthy sender reputation over time, which is a long-term strategy.
Key considerations
- Branding Consistency: Ensure consistent branding across subdomains to maintain a professional look.
- Brand Perception: Be aware that subdomains might dilute brand perception if not implemented carefully.
- Long-Term Strategy: Consider if using a subdomain aligns with your long-term email marketing strategy.
Marketer view
Email marketer from GMass responds by explaining that using a subdomain is a common way to send emails and protect the main domain's sender reputation. This ensures that if your marketing emails face deliverability issues, your primary domain is unaffected.
24 Apr 2024 - GMass
Marketer view
Email marketer from SparkPost shares that using a subdomain allows you to manage and protect your sender reputation separately from your main domain, which is crucial for maintaining deliverability and avoiding impact on business-critical emails.
5 Jun 2025 - SparkPost
What the experts say
8 expert opinions
The responses provide a nuanced perspective on choosing between a primary domain and a subdomain for sending email. While there's no definitive reason *not* to use a primary domain if authentication is properly set up and the client's goal is simply to have their domain in the 'From' header, several factors favor using a subdomain. These include isolating sender reputation, ensuring DMARC alignment with a proper return path, and facilitating testing of new email programs or vendors. A key consideration is clarifying the client's goals and risk tolerance regarding shared reputation. Proper SPF record setup is crucial, and unauthorized brand names in subdomains should be avoided.
Key opinions
- No Hard Rule: There's no definitive reason not to use a primary domain if authentication is correctly configured and the client wants the domain in the 'From' header.
- Reputation Isolation: Using a subdomain helps isolate sender reputation, preventing issues from impacting the primary domain.
- DMARC Alignment: A subdomain is crucial for ensuring proper DMARC alignment with a correct return path and SPF setup.
- Testing Advantage: Subdomains enable testing of new email programs, IPs, and vendors with less risk to the primary domain.
- SPF Importance: The client should not add Mailgun to their main SPF record; a separate SPF record for the subdomain is necessary.
Key considerations
- Client Goals: Clarify the client's objectives; what they want in the From: header and their understanding of the implications.
- Shared Reputation: Using the primary domain means sharing reputation with all other email streams from that domain, assess the risk.
- Authentication: Ensure the ESP supports proper authentication if the primary domain is used.
- Unauthorized Branding: Avoid including unauthorized brand names in subdomains to prevent filtering issues.
- 821.From: You have to have a subdomain of the brand in the 821.From for any of that to work well.
Expert view
Expert from Email Geeks notes that using the primary domain means sharing reputation between the client's mail stream and other mail using their main domain, which might be a problem if the client isn't conscientious.
11 Dec 2021 - Email Geeks
Expert view
Expert from Email Geeks advises to clarify that the client wants their domain in the From header, mention shared reputation as a reason for subdomains, and if they're okay with it, move forward with aligned authentication.
15 Nov 2021 - Email Geeks
What the documentation says
4 technical articles
The documentation provides a balanced view. While RFC 3834 emphasizes clear sender identification and consistent use of the domain for building trust (without specifically recommending primary or subdomain), Google Workspace Admin Help and MailChannels highlight the strategic benefits of using subdomains. These include segmenting email streams, testing purposes, and, most importantly, protecting the main domain's reputation, particularly for high-volume sending. DMARC.org underscores the importance of domain authentication to protect against unauthorized use.
Key findings
- Sender Identification: RFC 3834 emphasizes the importance of clear sender identification through the domain name.
- Consistency & Trust: Consistent domain usage builds trust with recipients.
- Strategic Use of Subdomains: Google Workspace Admin Help points to the benefits of subdomains for segmentation and testing.
- Reputation Protection: MailChannels highlights that subdomains protect the main domain's reputation, particularly for high-volume sending.
- Domain Authentication: DMARC.org underscores the importance of domain authentication to prevent spoofing.
Key considerations
- Trust Building: Prioritize building trust through consistent domain usage, regardless of primary domain or subdomain.
- Email Volume: Consider using a subdomain if sending high volumes of email to protect the main domain's deliverability.
- Email Segments: Subdomains are a good choice for segmenting email streams.
- Security: Regardless of the domain choice, proper domain authentication (SPF, DKIM, DMARC) is crucial.
Technical article
Documentation from Google Workspace Admin Help explains that you can add a subdomain to your Google Workspace account and set up custom email addresses with it. This can be beneficial for segmenting email streams or testing purposes, thereby suggesting a strategic use of subdomains.
4 Jan 2022 - Google Workspace Admin Help
Technical article
Documentation from MailChannels shares using a subdomain for high-volume email sending to avoid negative impact on the main domain's reputation and deliverability. If there are issues with the email being sent, it won't stop other important emails being sent from the main domain.
7 May 2022 - MailChannels
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