Summary
Using a single Email Service Provider (ESP), like Mailgun, for both internal system notifications and external transactional emails can raise concerns about deliverability. While transactional emails generally enjoy high inbox placement due to user expectation and engagement, the quality and engagement (or lack thereof) of internal system notifications can potentially impact the shared sender reputation, especially if both mailstreams originate from the same domain and IP address. Issues like high bounce rates from inactive employee email addresses or low engagement on internal alerts could subtly degrade the overall sending reputation, affecting the deliverability of critical transactional emails.
Key findings
- Shared infrastructure: Sending different types of email (transactional and internal notifications) from the same domain and IP address can lead to their reputations being intertwined. This means poor performance in one stream can affect the other.
- Engagement metrics: Low open rates, high bounce rates (due to inactive employee accounts), or spam complaints on internal notifications can negatively impact your sender reputation, which mailboxes like Gmail monitor closely. Google's algorithms consider various factors for email deliverability.
- Transactional email priority: Transactional emails (like order confirmations or password resets) are critical and highly anticipated by recipients. Their deliverability should be prioritized to ensure vital communications reach users.
- Mailstream segregation: While not always catastrophic, explicitly distinguishing mailstreams, perhaps through different DKIM domains or subdomains, can help email providers recognize them as separate entities, insulating transactional emails from potential issues caused by internal notifications.
Key considerations
- Audience and expectation: Transactional emails are expected by recipients, leading to high engagement. Internal notifications, especially if frequent or irrelevant to some recipients (e.g., ex-employees), may have lower engagement or even lead to complaints.
- List hygiene for internal sends: Regularly pruning email addresses of former employees from internal notification lists is crucial to avoid sending to dormant or non-existent accounts, which can generate bounces and harm sender reputation. For more on this, consider the impacts of email sending practices on domain reputation.
- Monitoring deliverability: Even if no immediate issues are apparent, consistent monitoring of deliverability metrics for both streams is essential. This includes keeping an eye on bounce rates, complaint rates, and inbox placement.
- ESP capabilities: While a single ESP can handle both, understanding how your ESP (e.g., Mailgun) manages different mailstreams and their IP allocation can inform decisions. Some ESPs automatically segregate based on content or stream type. Learn more about how your ESP affects deliverability.
- Strategic separation: If deliverability issues arise for transactional emails, consider gradually separating the internal notification stream onto a different sending domain or IP, or even a different ESP if necessary. This can help isolate any negative impacts. For further insight, check out our guide on whether transactional emails negatively impact marketing email deliverability.
What email marketers say
Email marketers often face the challenge of managing diverse email streams within a single ESP. When it comes to internal system notifications alongside critical transactional emails, a common concern is whether poor engagement or outdated lists for the former can compromise the deliverability of the latter. Marketers generally agree that while it's not ideal, it's manageable if proper hygiene and monitoring practices are in place, but outright separation is the safest bet for protecting transactional mail.
Key opinions
- Risk assessment: Many marketers acknowledge the inherent risk of combining mailstreams with vastly different engagement profiles, but some find it acceptable as long as deliverability issues aren't surfacing.
- Engagement divergence: The core problem lies in internal notifications often having lower engagement, or even bounces from stale addresses, which can send negative signals to ISPs that then impact the shared IP and domain reputation used for transactional emails.
- Monitoring is key: Continuous vigilance over deliverability metrics for both streams is frequently cited as crucial. If transactional email delivery starts to falter, the internal stream is often the first suspect.
- Segmentation benefits: Some marketers advocate for segmenting these email types, even if it's just by using a subdomain or a different sender email address, to help ISPs differentiate the traffic and assign separate reputations. For more on segmentation, refer to our article on improving deliverability by segmenting sends by provider.
Key considerations
- Prioritize transactional mail: The consensus is to protect transactional email deliverability at all costs due to its direct impact on user experience and business operations.
- Clean internal lists: Regularly update and clean lists for internal notifications to remove former employees and reduce bounces. This practice helps maintain a healthy sending reputation for your domain and IP, mitigating potential deliverability issues. This is also covered in our guide on why emails go to spam.
- Identify mailstreams: Work with your ESP to understand how they differentiate mailstreams. Using distinct subdomains or `From` addresses can sometimes help ISPs categorize your mail more effectively. Find out more about transactional email characteristics.
- Consider separate IPs/domains: If significant deliverability issues arise with transactional emails, the strongest recommendation is to use separate dedicated IPs or even domains for internal notifications to completely isolate their reputation from the transactional stream.
Marketer view
Email marketer from Email Geeks notes that their operations team uses the same ESP for both transactional emails to users and internal system notifications to employees. They are concerned that low engagement or sending to inactive internal addresses might negatively affect the deliverability of the transactional emails. This setup is heavily concentrated on the Gmail domain, as internal email addresses are GSuite-based. The marketer highlighted that both types of email have significant send volumes, raising the stakes for potential deliverability impacts. They questioned whether this shared infrastructure approach is considered a bad practice within the industry.
Marketer view
Email marketer from Shopify emphasizes that transactional emails are distinct from marketing emails. They highlight that transactional emails are automated, triggered by specific customer actions, and are expected communications like order confirmations, shipping updates, or password resets. These emails typically have high open rates due to their immediate relevance and necessity for the recipient. Therefore, maintaining excellent deliverability for these messages is paramount for customer satisfaction and business operations. Mixing them with less engaged internal notifications could introduce risks.
What the experts say
Deliverability experts generally agree that while combining transactional and internal notification email streams on the same ESP (and especially the same IP and domain) is not an immediate catastrophic error, it introduces significant risks. The primary concern revolves around how email service providers (like Gmail) perceive and score sender reputation based on engagement and bounce rates across all mail sent from a given infrastructure. If internal notifications suffer from low engagement or high bounces, these negative signals can spill over and adversely affect the highly critical transactional emails.
Key opinions
- Reputation isolation: Experts emphasize the importance of distinguishing mailstreams. Using different DKIM `d=` tags or even separate subdomains can help ISPs (like Google) recognize and treat them as distinct entities, thus potentially isolating their reputations.
- Poor hygiene impact: Poorly managed internal notification lists (e.g., sending to departed employees) lead to hard bounces and low engagement, which are strong negative signals that can damage shared IP and domain reputation.
- Gradual separation: If deliverability issues are not currently observed, experts often recommend a gradual transition towards separating mailstreams as a proactive measure, rather than waiting for problems to emerge.
- Non-catastrophic, but suboptimal: While not inherently 'terribly bad' in all cases, combining these streams is generally considered suboptimal from a deliverability best practice standpoint, particularly for high-volume senders using a single ESP. This is especially true for shared IP environments. Learn more about how ESPs impact deliverability on dedicated IPs.
Key considerations
- Active management of internal lists: Even for internal sends, maintaining active and current recipient lists is vital. Removing inactive or former employee addresses reduces bounce rates and preserves the overall sender reputation. This directly ties into your domain reputation with Google Postmaster Tools.
- Authentication practices: Ensuring proper SPF, DKIM, and DMARC alignment for both mailstreams, even if shared, is fundamental. Different DKIM selectors or domains can further differentiate the streams to receiving servers. Learn more about a simple guide to DMARC, SPF, and DKIM.
- Response to delivery issues: If transactional email deliverability issues are observed, separating the mailstreams becomes a necessary and immediate troubleshooting step to isolate the problem source.
- Long-term strategy: For long-term optimal deliverability and risk mitigation, especially for high-volume senders, establishing separate sending domains or IPs for internal notifications is a robust strategy. Read more on why your mail provider has deliverability issues.
Expert view
Deliverability expert from Email Geeks suggests that deliverability depends on whether Google recognizes transactional and internal notification emails as different mailstreams. They propose that using different DKIM `d=` parameters would be one way to explicitly signal to Google that these are distinct types of email. This approach helps in managing sender reputation more granularly, preventing issues from one stream affecting the other.
Expert view
Deliverability expert from Word to the Wise frequently advises that high bounce rates, particularly from non-existent addresses, are detrimental to sender reputation. They highlight that such bounces signal to ISPs that the sender's list hygiene is poor, which can lead to increased filtering or even blacklisting for all mail from that sender. Therefore, regularly cleaning internal lists, even for seemingly less critical communications, is a fundamental deliverability best practice.
What the documentation says
Official documentation from various Email Service Providers and email deliverability resources often provides best practices for managing different types of email streams. While direct guidance on internal system notifications specifically affecting transactional email on the same ESP might be limited, the underlying principles of sender reputation, list hygiene, and stream segregation are universally applicable. Documentation typically highlights that positive user engagement and low complaint/bounce rates are paramount for maintaining good standing with Internet Service Providers (ISPs), irrespective of the email's purpose. Any activity that negatively impacts these metrics, even from internal sends, can indirectly affect overall deliverability.
Key findings
- Sender reputation is unified: Many ESPs and ISPs treat mail sent from the same IP and domain (or even closely related subdomains) as having a single, unified reputation. Any negative signals from internal notifications contribute to this collective score.
- Engagement drives placement: Documentation often stresses that high engagement (opens, clicks) and low negative feedback (spam complaints, unsubscribes, bounces) are key factors for consistent inbox placement across all email types.
- Importance of list hygiene: Regularly removing invalid or inactive addresses is a foundational best practice mentioned across various documentation, crucial for preventing hard bounces that severely damage sender reputation.
- Authentication standards: Proper implementation of SPF, DKIM, and DMARC is consistently highlighted as essential for proving sender legitimacy and preventing spoofing, which indirectly aids overall deliverability by building trust. For an overview, see a simple guide to DMARC, SPF, and DKIM.
Key considerations
- Separate sending domains/subdomains: Many ESPs advise using distinct domains or subdomains for different mailstreams (e.g., marketing vs. transactional) to allow ISPs to build separate reputations for each, thus compartmentalizing risk. This approach is highly recommended for maintaining high deliverability for critical transactional emails.
- Monitor delivery reports: Regularly reviewing bounce reports, complaint loops, and engagement statistics provided by your ESP or through tools like Google Postmaster Tools is crucial for identifying potential issues early. This can help you understand DMARC reports from Google and Yahoo.
- Segmenting by purpose: Documentation often implicitly or explicitly suggests that emails with different purposes and audience expectations should ideally be handled distinctly to optimize their respective deliverability rates. For example, Bloomreach documentation discusses leveraging two ESP integrations for transactional emails to ensure high availability and independent routing.
Technical article
Documentation from Bloomreach Engagement outlines strategies for transactional email deliverability, emphasizing high availability through multiple ESP integrations. They suggest that using two ESPs evenly for sending transactional emails helps ensure reliability. This strategy implicitly supports segregating critical email streams to prevent a single point of failure or reputation issues from affecting all communications.
Technical article
The Twilio (SendGrid) documentation on marketing and transactional email dives into the nuances between transactional content, promotional emails, and hybrid types. It differentiates these email categories based on their purpose and audience expectation. This distinction highlights that different content types are processed differently by ISPs, reinforcing the idea that mixing them on the same sending infrastructure can complicate deliverability.
Related resources
15 resources
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