Summary
The consensus among email experts and marketers is that using subdomains is a beneficial strategy for protecting a main domain's reputation. While a subdomain's negative reputation can sometimes impact the main domain, segmentation of different email streams (transactional, promotional, bulk, and even internal communications) allows for better management and tracking. By separating email types, it reduces the risk of deliverability issues from one stream affecting others. The use of subdomains facilitates granular reputation management, provides a cost-effective alternative to dedicated IPs, and enables DKIM configuration for authentication, further enhancing deliverability. Proper planning and execution are critical to realizing the full benefits of subdomain segmentation. Isolating brand reputation helps ensure marketing blasts don't impact crucial transactional email delivery.
Key findings
- Reputation Isolation: Subdomains effectively isolate brand reputation, preventing marketing issues from negatively impacting transactional email delivery.
- Granular Management: Using subdomains allows for finer control over email sending reputation, improving deliverability.
- Authentication Benefits: DKIM configuration on subdomains enhances deliverability and authenticates email streams.
- Segmented Control: Subdomains enable separate tracking and management of email types, minimizing risk to the primary domain.
- Cost Effective: Subdomains provide a cost-effective alternative to dedicated IPs for reputation management.
Key considerations
- Potential Reputation Impact: A subdomain's negative reputation can potentially affect the main domain, requiring ongoing monitoring.
- Not Always Mandatory: For senders with strong opt-in practices, the benefit of subdomains may be marginal.
- Volume Dependent: The advantages of subdomain segmentation are more pronounced with higher email volumes.
- Strategy Execution: Proper planning and execution are critical to realizing the full benefits of subdomain segmentation.
- Careful Set-Up Required: Authentication (DKIM) requires proper implementation on each subdomain to achieve maximum deliverability gains.
What email marketers say
11 marketer opinions
The use of subdomains for separating transactional and promotional emails is a common strategy to protect the main domain's reputation. While some sources suggest that a subdomain's reputation can still impact the main domain, the overall consensus indicates that subdomains provide a degree of isolation. This segmentation allows for better tracking and management of email reputation for different email types, minimizing risk to the primary domain. Using subdomains offers a balance between control and cost-effectiveness, especially for those not ready to invest in dedicated IPs. A well-defined subdomain strategy is essential for deliverability, particularly for segmenting transactional, marketing, and bulk emails. Best practices include using distinct subdomains (e.g., transactional.yourdomain.com, marketing.yourdomain.com) and considering segmentation for internal communications as well. The primary advantage is the ability to contain deliverability issues, limiting the impact of spam complaints on the core domain and other subdomains. Additionally, proper setup and management are crucial to realize the benefits of subdomain segmentation effectively.
Key opinions
- Reputation Isolation: Subdomains provide a level of isolation, so issues with one subdomain are less likely to affect the entire domain's reputation.
- Segmentation Benefits: Using subdomains allows for better segmentation of email sending, improving tracking and management of reputation for different email types.
- Cost-Effectiveness: Subdomains offer a balance between control and cost-effectiveness compared to dedicated IPs.
- Containment of Issues: Subdomains can contain deliverability issues, limiting the impact of spam complaints on the core domain and other subdomains.
Key considerations
- Reputation Impact: A subdomain's reputation can potentially impact the parent domain, though the impact is typically less severe than if all emails were sent from the main domain.
- Volume Requirements: For sufficient volume, segmenting mail on 5321/5322/dkim can help, but it's difficult to know how each MBP handles domain reputation.
- Strategy Definition: A well-defined subdomain strategy is essential for deliverability, and proper setup and management are crucial for realizing the benefits effectively.
- Segmentation scope: Consider segmenting not only transactional and promotional emails but also internal communications to avoid crossover issues.
Marketer view
Email marketer from SendGrid mentions that subdomains allow for better segmentation of your email sending. By using different subdomains for transactional and promotional emails, you can better track and manage the reputation of each type of email, minimizing the risk to your primary domain.
9 Oct 2024 - SendGrid
Marketer view
Email marketer from Reddit shares that the key advantage of using subdomains lies in their ability to contain deliverability issues. If one subdomain is impacted by spam complaints, it will have a limited impact on your core domain and other subdomains.
14 Dec 2022 - Reddit
What the experts say
5 expert opinions
Experts generally agree that using subdomains is a good practice for managing email reputation, particularly for isolating different email streams such as transactional and promotional. Setting up authentication like DKIM with subdomains allows for reputation segregation without changing the user experience. While not always considered a 'best practice' in the 5322.from, using subdomains won't typically hurt deliverability, especially for opted-in recipients. For significant growth, fully separating subdomains with their own DKIM is recommended. This segmentation protects the core domain and allows granular management of sender reputation by using d= for DKIM signatures and separating emails by ESP.
Key opinions
- Isolation of Reputation: Subdomains effectively isolate brand reputation, preventing marketing issues from impacting transactional email delivery.
- Granular Management: Subdomains allow for more granular management of email sending reputation and improved deliverability.
- Authentication Options: Authentication methods like DKIM can be set up with subdomains without changing what the user sees.
- Growth Recommendation: For significant growth, fully separating subdomains with their own DKIM is recommended.
Key considerations
- Not Always a Best Practice: Using subdomains is not universally considered a 'best practice,' though it generally won't hurt deliverability.
- Opt-In Importance: For opted-in recipients, the chances of domain-based reputation problems are slim, regardless of subdomain use.
- DKIM Segmentation: Using d= for DKIM signatures and separating emails by ESP can further enhance subdomain segmentation.
- Fully Authenticated Subdomains: Ensuring subdomains are fully authenticated (with their own DKIM) is essential for maximum benefit.
Expert view
Expert from Spam Resource explains that using subdomains effectively isolates your brand reputation. This isolation helps ensure that problems with marketing blasts will not impact delivery of transactional email. The article advocates using subdomains to separate different sending streams and protect the core domain.
24 Feb 2022 - Spam Resource
Expert view
Expert from Word to the Wise, Laura Atkins, addresses that subdomains are a good idea to segregate streams of mail for reputation purposes, by segmenting using d= for DKIM signatures, different ESPs, etc. This allows for more granular management of your email sending reputation and improved deliverability.
23 Mar 2024 - Word to the Wise
What the documentation says
4 technical articles
Email deliverability documentation generally supports the use of subdomains for managing and protecting sender reputation. Google Workspace Admin Help recommends setting up separate subdomains to isolate reputation issues and manage email traffic. SparkPost suggests isolating promotional emails to protect the primary domain from potential deliverability problems. While Microsoft's documentation doesn't explicitly advocate for subdomains, it emphasizes segmenting email streams and monitoring reputation, which subdomains can facilitate. DKIM can be configured on subdomains to improve deliverability and authenticate emails, as noted in RFC documentation.
Key findings
- Reputation Isolation: Subdomains can help isolate reputation issues, preventing problems with one email stream from affecting others.
- Email Stream Separation: Subdomains are a common practice for separating email streams, particularly promotional and transactional emails.
- Authentication Support: DKIM can be configured on subdomains to improve deliverability and authenticate emails.
- Facilitates Segmentation: Subdomains facilitate segmenting email streams, which is emphasized as important for maintaining a good sender reputation.
Key considerations
- Explicit Advocacy: Not all documentation explicitly advocates for subdomains, but they generally support the underlying principles of segmentation and reputation management.
- Configuration Required: Setting up separate subdomains for different email types and configuring authentication methods requires careful planning and execution.
- Monitoring Needed: While subdomains help, it's still crucial to monitor the reputation of each subdomain to ensure optimal deliverability.
Technical article
Documentation from Google Workspace Admin Help explains that using subdomains can help organize and manage email traffic, potentially isolating reputation issues. They recommend setting up separate subdomains for different types of emails to protect the main domain's reputation.
23 Oct 2023 - Google Workspace Admin Help
Technical article
Documentation from Microsoft explains that maintaining a good sender reputation is crucial for email deliverability. While they don't explicitly advocate for subdomains, the document emphasizes the importance of segmenting email streams and monitoring reputation, which can be facilitated by using subdomains.
21 Sep 2024 - Microsoft
