The overwhelming consensus among experts, email marketers, and documentation sources is that utilizing multiple subdomains for different email streams is a best practice for managing sender reputation and improving email deliverability. The core benefit lies in isolating reputation; a negative reputation on one subdomain is less likely to affect others, especially critical transactional emails. Experts recommend separating email types like transactional, marketing, and bulk onto distinct subdomains. While some caution against excessive subdomain use, especially for smaller senders or due to the risk of "subdomain hopping" being flagged as snowshoe spamming, separating concerns by subdomain is a generally accepted strategy. Utilizing recipient-recognizable branding when naming subdomains and implementing separate IP pools per subdomain is also advised.
13 marketer opinions
The general consensus is that using multiple subdomains for different email streams is a beneficial practice for managing sender reputation and improving email deliverability. Segmenting email types, such as transactional, marketing, and bulk emails, onto separate subdomains helps isolate reputation issues, preventing deliverability problems from one email type from affecting others, particularly critical transactional emails. However, some caution against excessive subdomain use, especially for smaller senders, and warn about the risks of 'subdomain hopping,' which can lead to being flagged for snowshoe spamming. It's generally recommended to start with a well-managed subdomain and scale as needed.
Marketer view
Email marketer from SuperOffice suggests that to safeguard your email deliverability, segment your email traffic and sending IPs into separate subdomains to avoid sending email streams from the same domain. For example, you can send marketing newsletters from one subdomain and sales emails from another.
22 Nov 2022 - SuperOffice
Marketer view
Email marketer from StackExchange recommends using subdomains to segregate different types of emails. For example, use transaction.domain.com for transactional emails, marketing.domain.com for marketing emails, and so on. This helps to isolate reputation and prevent deliverability issues for one type of email from affecting others.
1 Dec 2024 - StackExchange
6 expert opinions
Experts generally agree that using multiple subdomains for different email streams offers benefits such as reputation isolation and enhanced deliverability. Separating email types (e.g., marketing, transactional) allows for isolated management of sender reputation. While high volume doesn't always necessitate numerous subdomains, it can help isolate Gmail issues. Experts recommend recipient-recognizable branding for subdomains and caution against failing all traffic to another subdomain if one is blocked. One expert also notes that, at a certain volume and configuration, multiple subdomains may be viewed as a shared IP pool.
Expert view
Expert from Word to the Wise highlights that sending marketing and transactional email from the same domain or subdomain puts your critical transactional messages at risk. It is crucial to separate email streams using distinct subdomains to protect the reputation of your transactional email.
8 Aug 2021 - Word to the Wise
Expert view
Expert from Spam Resource explains that using separate subdomains isolates reputation. If one subdomain develops a bad reputation due to specific campaigns or user behavior, it's less likely to impact the deliverability of emails sent from other subdomains.
17 Feb 2024 - Spam Resource
5 technical articles
The documentation sources consistently recommend using multiple subdomains for different email streams to improve organization, apply distinct policies, and isolate sender reputation. This approach protects critical transactional emails from deliverability issues associated with other types of email, such as marketing or promotional messages. The RFC Editor documentation provides the technical foundation for understanding the distinct nature and separate management of subdomains.
Technical article
Documentation from Google Workspace Admin Help explains that using subdomains can help organize email and apply different policies to different types of mail. For example, marketing emails can be sent from 'marketing.example.com' and transactional emails from 'transaction.example.com'.
27 Oct 2023 - Google Workspace Admin Help
Technical article
Documentation from Microsoft explains that sender reputation is tied to the domain/subdomain. Using dedicated subdomains for different mail streams can prevent issues with one stream from impacting the deliverability of other, more important email such as transactional messages.
12 Apr 2024 - Microsoft
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