Sending internal system notifications using the same ESP as transactional emails presents deliverability challenges. While not inherently catastrophic, the impact hinges on several factors. Mailbox providers assessing mail streams differently, proper email authentication (SPF, DKIM, DMARC), and maintaining impeccable list hygiene are critical. Internal notifications generating high spam rates, bounce rates, or SMTP errors can negatively impact sender reputation and domain/IP reputation, affecting transactional email deliverability. Segregating mail streams using dedicated IPs and different DKIMs, warming up IPs, and continuously monitoring IP/domain reputation are vital. Optimizing SMTP configurations is also beneficial.
9 marketer opinions
Sending internal system notifications using the same ESP as transactional emails can negatively impact deliverability. Factors such as shared IP reputation, list hygiene, authentication, engagement, and sender reputation are all affected. High bounce rates, spam complaints, and unauthenticated emails from internal notifications can damage the sender's reputation and subsequently harm the deliverability of transactional emails. Proper email authentication (SPF, DKIM, DMARC), maintaining clean email lists, segmenting mail streams, using dedicated IPs, warming up IPs, and monitoring IP reputation are key to mitigating these risks. Correctly configuring SMTP connections can also improve deliverability.
Marketer view
Email marketer from Reddit explains that poor list hygiene for internal notifications (sending to old or invalid addresses) can lead to high bounce rates. High bounce rates signal poor sending practices and can hurt your overall deliverability.
3 Aug 2023 - Reddit
Marketer view
Email marketer from Litmus Blog explains that proper email authentication (SPF, DKIM, DMARC) is crucial for establishing trust with mailbox providers. If internal notifications are not properly authenticated, they can be flagged as spam and impact your overall sending reputation.
29 Jun 2024 - Litmus Blog
4 expert opinions
Sending internal system notifications alongside transactional emails using the same ESP can impact deliverability, though it's not inherently catastrophic. The key is whether mailbox providers recognize the streams as distinct. Poorly managed internal lists and unwanted notifications can generate spam reports, harming sender reputation. Segregation of mail streams is advisable, especially if deliverability issues arise. Warming up a new IP address is essential for establishing a positive reputation when introducing new internal email systems.
Expert view
Expert from Spamresource explains that a poorly managed list is a huge cause of spam reports. If a business' internal email list is poorly maintained, and emails are sent to addresses that are not expecting them, this can generate high spam complaints which will affect the sender's reputation and impacting transactional emails.
17 May 2022 - Spamresource
Expert view
Expert from Email Geeks explains that whether the different mail streams affect deliverability depends on if Google recognizes them as different. Different DKIM d= would be one way to explicitly announce they’re different. Also to fix badly handled internal campaigns.
18 Jun 2021 - Email Geeks
4 technical articles
Sending internal system notifications can affect transactional email deliverability through several mechanisms. SMTP errors from invalid recipients can harm sender reputation. High spam rates from irrelevant content or outdated lists in internal notifications negatively impact domain reputation with major providers like Gmail. Monitoring IP reputation via Microsoft SNDS is crucial, as issues with internal notifications can impact reputation with Outlook and Hotmail. Maintaining low bounce rates by promptly removing hard bounces and repeatedly soft-bouncing addresses from both internal and external lists is also critical for preserving sender reputation.
Technical article
Documentation from SparkPost explains that to maintain low bounce rates to keep a good sender reputation it is important to remove addresses that hard bounce immediately. Also it is important to remove emails that have soft bounced multiple times. This is important for internal and external lists.
3 May 2025 - SparkPost
Technical article
Documentation from Microsoft SNDS shares that monitoring your IP reputation is essential for understanding how Microsoft views your sending practices. Issues with internal notifications can impact your IP's reputation with Outlook and Hotmail.
8 Aug 2022 - Microsoft
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