Summary
The general consensus is that using subdomains to segment email streams is a valuable strategy for enhancing deliverability and protecting sender reputation. Subdomains enable isolation of reputation, ensuring that deliverability issues in one stream don't negatively impact others. This is particularly beneficial for safeguarding critical transactional emails from problems affecting marketing campaigns. ISPs favor subdomains because they facilitate more selective filtering of email. Key to successful implementation is establishing and maintaining a strong sending reputation for each subdomain, which includes consistently sending valuable content, engaging in responsible email practices, and properly configuring DKIM. Warming up new subdomains is crucial, and varying the DKIM d= value while using the same domain in the 'from' address can be effective. The decision to use subdomains also depends on the 'cleanliness' of your existing email program; if it's already well-managed, the benefits may be less significant. Therefore, assess your specific goals, risks, and business needs before implementing this strategy.
Key findings
- Reputation Isolation: Subdomains isolate sending reputation, preventing issues in one email stream from affecting others, especially protecting transactional emails.
- ISP Preference: ISPs prefer subdomains for more selective filtering, allowing for better deliverability management.
- DKIM Importance: The DKIM 'd=' value is a strong indicator for segmentation, more so than the local part of the email address.
- Program Cleanliness: If your email program is already well-managed and has a good reputation, the benefits of subdomains might be less significant.
- Organization: Subdomains allow you to organize your online presence and improve deliverability by isolating reputation for different email streams.
Key considerations
- Assess Program Cleanliness: Evaluate whether your existing email program is already well-managed; if so, the benefits of subdomains might be marginal.
- Subdomain Warmup: Properly warm up new subdomains to establish a positive sending reputation.
- DKIM Configuration: Consider using the same domain in the 'from' address but vary the DKIM 'd=' value for effective segmentation.
- Valuable Content: Consistently send valuable content that recipients want and expect.
- Responsible Practices: Engage in responsible email practices, such as respecting unsubscribe requests and avoiding spam triggers.
- Business Objectives: Determine your specific business goals, assess potential risks, and evaluate whether subdomains are the best strategy to achieve them.
What email marketers say
10 marketer opinions
The consensus among email marketers is that using subdomains to segment email streams is a beneficial strategy for improving deliverability and protecting sender reputation. By separating different types of emails (e.g., transactional vs. marketing) onto distinct subdomains, senders can isolate reputation issues and prevent deliverability problems in one stream from negatively impacting others. Maintaining consistent sending practices, authenticating emails, and monitoring subdomain reputation are important considerations.
Key opinions
- Reputation Isolation: Subdomains isolate sending reputation, ensuring that deliverability issues in one email stream don't affect others.
- Transactional Protection: Segmenting transactional and marketing emails onto different subdomains protects critical transactional messages from negative impacts.
- Improved Deliverability: A well-structured subdomain setup can improve overall email deliverability by isolating reputation.
- Sender Reputation: Maintaining consistent sending practices and engaging content improves overall sender reputation which can be achieved with subdomains.
Key considerations
- Email Authentication: Consistently authenticating emails helps to establish a positive sender reputation and improve deliverability.
- Sender Practices: Consistent sending practices, such as low spam rates, and low bounce rates, and engaging content are critical for a positive sender reputation.
- Reputation Monitoring: Monitoring each subdomain's reputation is important to ensure optimal deliverability and quickly address any issues.
Marketer view
Email marketer from Litmus responds that using subdomains helps protect your overall sender reputation. If one subdomain experiences issues, it's less likely to negatively impact the deliverability of emails sent from other subdomains.
19 Jun 2022 - Litmus
Marketer view
Email marketer from GlockApps shares that having a well-structured subdomain setup can improve email deliverability. They recommend using separate subdomains for different types of emails, and monitoring the reputation of each subdomain individually.
1 Sep 2022 - GlockApps
What the experts say
9 expert opinions
Experts generally agree that subdomains are useful for segmenting email streams and managing reputation, particularly for protecting transactional emails from marketing-related deliverability issues. However, if your email program is well-managed and clean, the benefits may be less significant. ISPs use subdomains to selectively filter mail. The DKIM d= value is a strong indicator for segmentation, more so than the local part of the email address. Warming up new subdomains is crucial, and using the same domain in the from address while varying the DKIM d= value can be an effective strategy. Double DKIM signing can also aid in warming up new DKIM domains.
Key opinions
- Reputation Isolation: Subdomains help isolate reputation, preventing issues in one email stream from affecting others.
- ISP Filtering: ISPs prefer subdomains for more selective filtering of email streams.
- DKIM Importance: The DKIM d= value is a stronger indicator for segmentation than the local part of the email address.
- Clean Programs: If your email program is already well-managed, the benefits of subdomains may be less noticeable.
Key considerations
- Program Cleanliness: Assess whether your email program is already well-managed; if so, the benefits of subdomains may be marginal.
- Subdomain Warmup: Properly warm up new subdomains to establish a positive reputation.
- DKIM Configuration: Consider using the same domain in the from address but varying the DKIM d= value for effective segmentation.
- Business Goals & Risks: Determine what your goals are, what are the risks and what is going to best serve your business.
Expert view
Expert from Email Geeks explains that the recommendation for separate subdomains is often about protecting some mail streams from bad behavior by other mail streams. However, if your program is pretty clean, then you might not need subdomains.
22 Jun 2023 - Email Geeks
Expert view
Expert from Email Geeks advises that you will need to warm up new subdomains. Suggests using the same domain in the from address, but use subdomains for the DKIM d= value. By doing this, you will make the d= the primary key for reputation and you can use <mailto:updates@emaildomain.com|updates@emaildomain.com> with a d=<http://updates.emaildomain.com|updates.emaildomain.com|updates@emaildomain.com>.
29 May 2022 - Email Geeks
What the documentation says
3 technical articles
Technical documentation highlights that subdomains are a viable way to organize your online presence and differentiate email sending streams, which can improve deliverability by isolating reputation. Establishing a good sending reputation for both your domain and subdomains is crucial, and should include sending valuable content consistently and engaging in responsible email practices. DomainKeys Identified Mail (DKIM) enables verification of email authenticity, and subdomains can be used to differentiate signing domains for distinct mail streams.
Key findings
- Reputation Building: Establishing a good sending reputation for both your domain and subdomains is essential for email deliverability.
- Organization and Isolation: Subdomains allow you to organize your online presence and improve deliverability by isolating reputation for different email streams.
- DKIM Differentiation: Subdomains can be used to differentiate signing domains for different mail streams using DomainKeys Identified Mail (DKIM).
Key considerations
- Valuable Content: Consistently send valuable content that recipients want.
- Responsible Practices: Engage in responsible email practices, such as respecting unsubscribe requests and avoiding spam triggers.
- DKIM Implementation: Properly configure DomainKeys Identified Mail (DKIM) to authenticate your emails and improve deliverability.
Technical article
Documentation from RFC explains that DomainKeys Identified Mail (DKIM) permits a signing domain to indicate administrative responsibility for signed messages. This allows recipients to verify the authenticity of the email, and subdomains can be used to differentiate signing domains for different mail streams.
17 Sep 2024 - RFC Editor
Technical article
Documentation from Microsoft explains that subdomains allow you to organize your online presence. You can use subdomains to host separate sections of your website, like a blog or store, or to differentiate between different email sending streams. This can improve deliverability by isolating reputation.
21 Jul 2024 - Microsoft
Can I use the same subdomain for multiple email sending platforms?
Do I need to add all subdomains to Google Postmaster Tools?
Do subdomains need their own DMARC records if the main domain has one?
How do I set up SPF and DKIM records for new subdomains when using third-party email services?
How do subdomain deliverability issues affect parent domains, and what are the primary causes of email deliverability problems?
Should I use subdomains for transactional and promotional emails to protect my main domain reputation?
