Should I use separate subdomains for marketing and transactional emails?

Summary

Email marketers, experts, and documentation from ESPs and inbox providers overwhelmingly recommend using separate subdomains (or even domains and IPs) for marketing and transactional emails. This strategy protects the primary domain's reputation by isolating deliverability issues. It also allows for segmented monitoring, improved email classification by ISPs, distinct authentication methods, and dedicated feedback loops. Sufficient email volume in both categories is a consideration, as the definition of 'sufficient' varies by target domain.

Key findings

  • Reputation Isolation: Using separate subdomains isolates the reputation of marketing and transactional emails, preventing issues in one stream from impacting the other.
  • Primary Domain Protection: Separate subdomains protect the main domain's reputation, particularly ensuring critical transactional emails are not affected by marketing campaigns.
  • Segmented Monitoring: Using subdomains allows for separate performance monitoring and targeted troubleshooting of deliverability issues specific to each email type.
  • ISP Classification: Different subdomains may assist ISPs in classifying emails into the appropriate inbox folders.
  • Distinct Authentication: Enables the use of different authentication methods (like DKIM) for each type of email.

Key considerations

  • Sufficient Volume: Sufficient email volume in both marketing and transactional streams is needed to justify separate subdomains; the definition of 'sufficient' depends on the target domain.
  • Implementation Complexity: Setting up and managing separate subdomains (or domains/IPs) requires more technical expertise and resources.
  • Dedicated Feedback Loops: Requires managing dedicated feedback loops and suppression lists for each stream.

What email marketers say
14Marketer opinions

The consensus among email marketers and experts is that using separate subdomains for marketing and transactional emails is highly recommended. This practice isolates sender reputation, protects main domain health, allows for segmented performance monitoring, and helps in classifying email types appropriately by ISPs. Sufficient volume is needed to justify subdomain separation, with the amount varying based on the target domain.

Key opinions

  • Reputation Isolation: Separate subdomains isolate the reputation of marketing and transactional emails, preventing issues with one from affecting the other.
  • Main Domain Protection: Using subdomains protects the main domain's reputation, ensuring critical transactional emails remain unaffected by marketing campaign deliverability issues.
  • Segmented Monitoring: Subdomains enable segmented performance monitoring, allowing for targeted troubleshooting of deliverability issues specific to each email type.
  • ISP Classification: Separate subdomains can assist ISPs in classifying emails into appropriate inbox folders, improving overall deliverability.

Key considerations

  • Sufficient Volume: Sufficient email volume in both marketing and transactional streams is necessary to justify the use of separate subdomains.
  • Target Domain: The definition of 'sufficient volume' is dependent on the target domain and its reputation requirements.
  • DKIM signing: Use DKIM signing when implementing subdomains.
Marketer view

Marketer from Email Geeks recommends that, assuming sufficient volume in both, its 100% recommended.

June 2021 - Email Geeks
Marketer view

Email marketer from Mailgun Blog explains that using subdomains for different types of emails (marketing vs. transactional) helps isolate reputation. If your marketing emails have deliverability issues, it won't affect your transactional emails.

April 2024 - Mailgun Blog
Marketer view

Email marketer from StackExchange user User123 explains that using subdomains for marketing and transactional emails allows you to build separate reputations for each type of email, increasing the likelihood of emails reaching the inbox.

May 2022 - StackExchange
Marketer view

Email marketer from ActiveCampaign Blog shares that using subdomains helps segment your email traffic. This segmentation allows you to monitor the performance of each type of email separately and address any deliverability issues without affecting other email streams.

August 2024 - ActiveCampaign Blog
Marketer view

Marketer from Email Geeks says separating mail streams with different subdomains is a good and common practice.

May 2024 - Email Geeks
Marketer view

Email marketer from ConvertKit shares that using subdomains will protect your primary domain's sender reputation. It allows you to troubleshoot deliverability issues independently without impacting other email streams.

November 2023 - ConvertKit
Marketer view

Marketer from Email Geeks explains that what is considered sufficient volume is really quite dependent on the target domain. Where it could be 1,000 for X, could be 10,000 for Y, but if you're numbering in the thousands total, you should be fine.

March 2023 - Email Geeks
Marketer view

Marketer from Email Geeks agrees from a deliverability standpoint. It may also help ISPs classify email in the appropriate inbox folder (in Gmail, Outlook,...).

December 2021 - Email Geeks
Marketer view

Email marketer from Gmass explains that the general recommendation is to use a subdomain for cold email outreach (marketing emails). If you make a mistake with your cold email outreach, it won't affect your main domain's reputation.

August 2024 - Gmass
Marketer view

Email marketer from Litmus Blog emphasizes the importance of using separate subdomains to manage different email streams effectively. It highlights that this practice allows for better monitoring and troubleshooting of deliverability issues specific to each email type.

May 2021 - Litmus Blog
Marketer view

Email marketer from Customer.io shares that they recommend using a separate sending domain for marketing and transactional emails for greater control over deliverability.

December 2022 - Customer.io
Marketer view

Email marketer from Reddit user u/EmailPro shares that by using different subdomains, you can isolate any reputation damage caused by marketing campaigns, protecting the deliverability of important transactional emails.

May 2024 - Reddit
Marketer view

Marketer from Email Geeks shares that it's a good idea to separate mail streams with different sub-domains and matching DKIM signing.

July 2023 - Email Geeks
Marketer view

Email marketer from Email on Acid Blog explains that separating marketing and transactional emails onto different subdomains helps protect the reputation of your main domain. If your marketing emails encounter deliverability issues, your transactional emails—which are critical for user experience—remain unaffected.

April 2022 - Email on Acid Blog

What the experts say
2Expert opinions

Experts recommend using separate subdomains (or even separate domains and IPs) for marketing and transactional emails. This allows for distinct authentication methods and the use of dedicated feedback loops and suppression lists. The primary goal is to isolate transactional emails, ensuring their reliable delivery.

Key opinions

  • Isolation: Separating email types by subdomain/domain isolates transactional sends, ensuring they are not impacted by marketing campaigns.
  • Different IPs & Authentication: Using separate subdomains or domains facilitates the use of different IPs and authentication methods for different email types.
  • Dedicated Feedback Loops: Segmentation allows the use of dedicated feedback loops and suppression lists for each email type.

Key considerations

  • Implementation Complexity: Implementing separate subdomains/domains and IPs requires more complex setup and management.
  • Resource Allocation: Consider the resources needed to manage and monitor multiple sending infrastructures.
Expert view

Expert from Spamresource explains that many companies use different subdomains for different classes of mail, for example transactional vs marketing. This allows the business to send from different IPs and use different authentication for different classes of mail.

May 2023 - Spamresource
Expert view

Expert from Word to the Wise advises using separate IPs and domains to handle marketing vs transactional emails and implement dedicated feedback loops and suppression lists. This isolates your transactional sends, which must get through.

March 2025 - Word to the Wise

What the documentation says
4Technical articles

Email service providers (SendGrid, SparkPost) and inbox providers (Google, Microsoft) documentation recommends separating email streams, using either separate subdomains or domains, for marketing and transactional emails. This protects the primary domain's reputation, improves deliverability, isolates deliverability issues, and ensures the reliability of transactional emails.

Key findings

  • Reputation Protection: Separate sending domains/subdomains protect the primary domain's reputation.
  • Improved Deliverability: Separation improves email deliverability overall.
  • Issue Isolation: Separating email streams isolates deliverability issues.
  • Transactional Reliability: Ensures the reliability of transactional emails.

Key considerations

  • Setup Complexity: Setting up and managing separate subdomains/domains requires technical expertise.
  • Domain Management: Consider the effort needed to manage multiple domains/subdomains and their authentication.
Technical article

Documentation from SparkPost Documentation suggests separating sending domains or subdomains for different email streams as a best practice for managing sender reputation and improving deliverability. This is particularly useful for isolating transactional emails from marketing campaigns.

November 2024 - SparkPost Documentation
Technical article

Documentation from Microsoft recommends to use different domains for different purposes, like transactional and marketing. This ensures that any deliverability issues with marketing won't affect the reliability of transactional emails.

February 2024 - Microsoft
Technical article

Documentation from SendGrid Documentation recommends using separate subdomains to send different types of email (e.g., marketing and transactional) to protect your primary domain's reputation and improve deliverability.

May 2022 - SendGrid Documentation
Technical article

Documentation from Google Postmaster Tools Help suggests that using separate sending domains/subdomains can help isolate deliverability issues and maintain a healthy sender reputation, particularly when sending different types of emails.

June 2024 - Google Postmaster Tools Help