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Can I use two subdomains on one dedicated IP address for different email types?
Summary
Using multiple subdomains on a single dedicated IP address for different email types (e.g., transactional and marketing) is a generally recommended strategy for improved email deliverability and sender reputation management. Subdomains enable segmentation of email traffic, allowing for the building of independent reputations and isolation of deliverability issues. To further separate treatment of mail streams, different DKIM signatures can be used, and different SPF records provide flexibility in authentication. While subdomains offer benefits, the IP address's overall reputation remains key. Careful monitoring of both the IP address and each subdomain's performance is crucial, as poor performance on one subdomain can negatively affect the entire IP's reputation. Low sending volumes may extend subdomain warmup periods, and it is important that ALL subdomains are compliant or it may impact your deliverability.

Key findings

  • Viability: Using subdomains on a single dedicated IP is a viable strategy.
  • Segmentation: Subdomains segment email traffic for improved reputation management.
  • Reputation Isolation: Subdomains build independent reputations and isolate deliverability issues.
  • Control: Allows better control over deliverability and sender reputation.
  • Flexibility: Different SPF records and DKIM signatures provide authentication flexibility.

Key considerations

  • IP Reputation: Maintaining a good IP address reputation is crucial.
  • Reputation Monitoring: Monitor the reputation of both the IP address and each subdomain.
  • Performance Impact: Poor performance on one subdomain can negatively affect the IP reputation.
  • Volume: Low sending volumes may result in longer subdomain warmup periods.
  • Compliance: All subdomains must be compliant with email sending best practices.
What email marketers say
10 marketer opinions
Using multiple subdomains on a single dedicated IP address for different email types (e.g., transactional and marketing) is a common and generally accepted strategy to improve email deliverability and manage sender reputation. By segmenting email traffic onto separate subdomains, senders can build independent reputations for each email type, isolate deliverability issues, and protect the main domain's reputation. However, it is crucial to monitor the reputation of both the IP address and each subdomain individually, as poor performance on one subdomain can affect the overall IP reputation. It allows for better management of bounces and unsubscribes for marketing purposes. If your subdomains do not meet best sending practices, it may impact your deliverability.

Key opinions

  • Segmentation: Subdomains allow for segmenting email types (transactional vs. marketing) for better reputation management.
  • Reputation Isolation: Separate subdomains build independent reputations, isolating deliverability issues.
  • Deliverability Improvement: Segmenting email traffic improves overall email deliverability.
  • Protects Main Domain: Subdomains protect the main domain's reputation from negative impacts.

Key considerations

  • Reputation Monitoring: Monitor the reputation of both the IP address and each subdomain individually.
  • Performance Impact: Poor performance on one subdomain can negatively impact the overall IP reputation.
  • Compliance: ALL your subdomains should be compliant and following best sending practices.
Marketer view
Email marketer from Automizy Blog explained that utilizing subdomains can improve inbox placement, and using different subdomains will allow better control over deliverability and sender reputation. It's helpful to separate transactional emails from promotional ones.
25 Aug 2021 - Automizy Blog
Marketer view
Email marketer from Gmass forum shared how using multiple subdomains for different email types on one IP address can improve deliverability, as it allows you to build separate reputations for each type of email, improving overall sending reputation.
23 Jun 2021 - Gmass forum
What the experts say
3 expert opinions
Experts agree that using subdomains on the same IP address is a good practice for segmenting mail streams and managing reputation. Separating transactional and marketing emails prevents the negative impact of marketing campaigns from affecting transactional deliverability. To encourage separate treatment of these mail streams, different DKIM signatures can be used. Additionally, different SPF records for each subdomain can provide flexibility in authenticating various mail streams. However, low sending volumes may result in a longer warmup period for the subdomains. Compliance across ALL subdomains is critical, as non-compliance will negatively impact deliverability.

Key opinions

  • Segmentation: Using subdomains segments mail streams for better reputation management.
  • Authentication: Different DKIM signatures and SPF records can be used for each subdomain.
  • Deliverability: Separating mail streams prevents marketing campaigns from affecting transactional deliverability.

Key considerations

  • Volume: Low sending volumes may result in longer warmup periods for subdomains.
  • Compliance: ALL subdomains must be compliant, or deliverability will be impacted.
Expert view
Expert from Email Geeks explains that to encourage separate treatment of mail streams, use different d= in the DKIM signatures.
5 Mar 2022 - Email Geeks
Expert view
Expert from Spam Resource explains that using subdomains on the same IP can segment reputation. Separating transactional and marketing mail this way prevents the negative impact of marketing campaigns from affecting transactional deliverability. But you should consider the volume you are sending as a whole - if low volumes your subdomains will take a long time to warm up.
25 Sep 2024 - Spam Resource
What the documentation says
5 technical articles
Using subdomains to segment email streams can help to isolate issues and manage deliverability. While maintaining a good IP address reputation is key, dividing traffic into different subdomains facilitates better organization, tracking, and reputation management. Correctly setting up SPF records is also important to use multiple subdomains. Sending consistent email, having low bounce and complaints is important.

Key findings

  • Isolation: Subdomains help isolate email streams and issues.
  • Organization: Subdomains improve organization and tracking.
  • Reputation Management: Segmenting via subdomains improves reputation management.

Key considerations

  • IP Reputation: Maintaining a good IP address reputation is essential.
  • SPF Records: Correctly configure SPF records for multiple subdomains.
  • Consistent Email: Send consistent email and have low bounce and complaints
Technical article
Documentation from SparkPost Documentation explains that sending different types of email (e.g., transactional and marketing) from the same IP address can impact deliverability if one type performs poorly. Subdomains can help isolate these streams, but ultimately, the IP address's reputation is key.
20 Jun 2023 - SparkPost Documentation
Technical article
Documentation from RFC explains the technical implications of SPF records when using multiple subdomains. This is applicable if you are managing SPF records and need to correctly set them up for multiple subdomains on a single IP.
19 Jan 2022 - RFC
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