Summary
Separating marketing and transactional emails onto distinct subdomains is a widely recommended practice in the email deliverability community. This strategy helps to isolate the reputation of different email streams, preventing potential issues with one stream (like marketing emails encountering low engagement or spam complaints) from negatively impacting the critical deliverability of the other (transactional emails). While not always strictly necessary for very low-volume senders, it becomes increasingly beneficial as email volume grows and engagement metrics diverge between email types. It can also aid in clearer classification by internet service providers (ISPs) and simplify tracking.
Key findings
- Reputation isolation: Using separate subdomains helps protect the positive reputation of transactional emails (high engagement) from the potentially lower engagement or higher complaint rates of marketing emails. This segregation is crucial for maintaining strong deliverability across different email types.
- ISP classification: ISPs (like Gmail and Outlook) can better classify incoming mail, potentially directing transactional emails to the primary inbox and marketing emails to promotional tabs, improving inbox placement for both.
- Volume dependency: The benefits of subdomain separation are most pronounced for senders with sufficient email volume in both streams. For very small volumes, the impact might be less critical.
- Authentication alignment: Proper configuration of email authentication protocols like DMARC, SPF, and DKIM for each subdomain is essential to ensure legitimate emails are recognized and delivered.
Key considerations
- Deliverability strategy: Consider your overall email deliverability strategy and how subdomain separation aligns with your sending volumes and campaign types.
- Monitoring and maintenance: Each subdomain requires separate monitoring for reputation and performance. This includes keeping an eye on engagement rates and any blacklist listings.
- Sender reputation: Recognize that separating streams helps maintain distinct sender reputations, meaning poor performance on one subdomain won't necessarily taint the others.
- Technical setup: Implementing subdomains requires proper DNS configuration for SPF, DKIM, and DMARC records for each, which can add complexity.
What email marketers say
Email marketers generally agree that separating marketing and transactional email streams onto different subdomains is a sound strategy for improving deliverability. They emphasize the importance of this separation to prevent negative impacts from promotional campaigns (which often have lower engagement) on critical transactional emails (like password resets or order confirmations), which must reach the inbox reliably. Many see it as a common and effective practice, especially when dealing with sufficient sending volumes.
Key opinions
- Common practice: Many marketers view separating mail streams with different subdomains as a good and widely adopted practice, especially when the volumes are significant enough to warrant it.
- Deliverability focus: The primary driver for this separation is improved deliverability, ensuring that critical transactional messages are not impacted by the performance of marketing campaigns.
- Inbox placement: Separating subdomains can help ISPs classify email more effectively, aiding in appropriate inbox placement (e.g., primary vs. promotions tab).
- Reputation protection: It serves as a protective measure; if a marketing subdomain encounters deliverability issues (e.g., gets blacklisted), the transactional subdomain remains unaffected, safeguarding vital communications.
Key considerations
- Sufficient volume: Marketers recommend this approach for organizations with sufficient email volume for both marketing and transactional streams. Without adequate volume, building a solid reputation for each subdomain can be challenging.
- Long-term protection: This strategy offers a future-proofing benefit, ensuring that potential deliverability penalties on marketing emails do not compromise essential transactional messages.
- Strategic decision: The decision to move promotional campaigns to a dedicated subdomain should be a strategic one, weighing the benefits against the operational overhead.
- Engagement impact: Understanding how user engagement differs between transactional and marketing emails is key to leveraging separate subdomains effectively. This helps in tailoring sender reputation for each.
Marketer view
Marketer from Email Geeks suggests that their previous email service provider (ESP) representative recommended setting up two different sending domains, one for marketing emails and another for transactional emails.
Marketer view
A marketer from Email Geeks asks about what constitutes sufficient volume for separating email streams, expressing a hunch about being in a 'fragile' middle ground for reputation due to volume.
What the experts say
Email deliverability experts strongly advocate for separating marketing and transactional email streams using different subdomains. Their consensus is that this strategy is crucial for maintaining distinct sender reputations, protecting high-priority transactional emails from potential deliverability issues arising from marketing campaigns. Experts also highlight that this approach can assist ISPs in proper email classification and that the impact on deliverability can vary depending on the target domain and the overall sending volume.
Key opinions
- Stream separation: It is a widely accepted best practice to separate mail streams with distinct subdomains, ensuring that different types of emails build their own reputations.
- Reputation management: This separation is key for managing sender reputation, as performance issues (like low engagement or complaints) on one subdomain will not automatically affect the others.
- ISP classification benefits: Experts agree that subdomain separation can assist ISPs in classifying emails into appropriate inbox folders, enhancing overall inbox placement.
- Volume considerations: The effectiveness of separating subdomains is often dependent on having sufficient sending volume for each stream to establish a stable reputation.
Key considerations
- Target domain variability: What constitutes 'sufficient volume' for reputation building can vary significantly based on the target domain (e.g., Gmail, Outlook), as each mailbox provider (MBP) has its own evaluation formulas.
- Reputation system specifics: The direct effect of volume on reputation and whether larger volume senders are favored is entirely dependent on the specific MBP's reputation system, as these systems differ.
- Proactive protection: Separating streams is a proactive measure to ensure that the primary domain's reputation remains intact regardless of potential issues on a marketing subdomain.
- Strategic implementation: Implementing subdomains requires careful planning to ensure proper authentication (SPF, DKIM) and alignment for each stream to maximize deliverability benefits.
Expert view
Deliverability Expert from Email Geeks confirms that separating mail streams with different subdomains and matching DKIM signing is a good idea for email deliverability.
Expert view
Expert from Email Geeks states that separating mail streams with different subdomains is a good and common practice in the industry.
What the documentation says
Official documentation and industry guides frequently advocate for using separate subdomains for different email streams. This recommendation stems from a fundamental understanding of how domain reputation is built and maintained by mailbox providers. By segmenting email types, senders can ensure that high-priority transactional emails benefit from a consistently strong reputation, while marketing emails, which may have varying engagement, do not compromise the deliverability of essential communications. This approach is consistent with best practices for email authentication and compliance.
Key findings
- Reputation management principle: Documentation supports the idea that subdomains allow for independent reputation building and management, crucial for diverse email sending activities.
- Deliverability improvement: Many guides highlight that separating transactional and marketing emails helps improve overall deliverability and ensures critical messages bypass spam filters.
- Protection against blocklists: Using separate subdomains can prevent a marketing campaign's poor performance (leading to a blacklist listing) from affecting the deliverability of transactional emails.
- Enhanced tracking: Separation enables more granular tracking and analysis of performance metrics for each email stream, aiding in optimization.
Key considerations
- Domain reputation isolation: Official documentation from email service providers often stresses that separating subdomains allows for the isolation of domain reputation, preventing issues from impacting all email types.
- Engagement level differences: Transactional emails typically have higher engagement rates than marketing emails, and subdomains protect this positive engagement metric from dilution.
- Email authentication setup: Each subdomain requires proper configuration of authentication records like SPF, DKIM, and DMARC to ensure compliance and improve deliverability. This is a crucial technical step to enhance deliverability.
- Strategic email communication: Documentation advises using subdomains for better segmentation of communication to maintain consistent engagement levels across different recipient groups.
Technical article
Documentation from Mailgun explains that separating promotional emails from transactional ones via new subdomains can help protect your overall sending domain's reputation.
Technical article
SAP Community documentation highlights that separating a transactional subdomain can contribute to improving delivery speed and, consequently, user experience and satisfaction.
Related resources
9 resources
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