Should I use multiple subdomains for different email streams or a single stream?

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.

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.

Email marketer from Email On Acid shares that using subdomains for different email types helps you maintain a cleaner sending reputation. For example, separate subdomains for transactional, marketing, and bulk emails can help isolate issues and ensure critical emails are delivered.

Email marketer from Mailjet shares that using subdomains for different email streams allows you to isolate reputation. If one subdomain gets a negative reputation due to a specific campaign, it won't necessarily affect the reputation of your other subdomains and main domain.

Email marketer from SendGrid explains that using subdomains lets you segment your email sending reputation. Transactional emails should come from a different subdomain than marketing emails. This protects your critical transactional emails from deliverability issues related to marketing sends.

Email marketer from Email Geeks suggests that while using multiple subdomains for the same type of email is possible, it could be harmful. Neil emphasizes that the problem follows the mail stream and introduces more variables. However, Neil agrees that separating concerns by subdomain is a best practice.

Email marketer from Email Geeks advises against multiple subdomains for a single mail stream due to the risk of being blocked for snowshoeing. Vytis warns that this activity could lead to the TLD being blocked, and that a stable reputation (good or bad) is more important for high-volume senders.

Email marketer from Reddit explains that using multiple subdomains is good for segmenting email reputation but can be overkill for smaller senders. The marketer advises starting with a single well-managed subdomain and only splitting it when the volume justifies the complexity.

Email marketer from Email Geeks raises concerns about "subdomain hopping" and suggests repairing the reputation of existing subdomains instead. Shad suggests that failing over millions of emails would require a warm-up phase and cautions against tarnishing the parent domain. Instead, Shad suggests dedicating IP pools for alerts, users, and marketing emails on their own subdomains.

Email marketer from Email Marketing Forum recommends setting up at least two subdomains: one for transactional emails (e.g., 'txn.yourdomain.com') and another for marketing emails (e.g., 'mkt.yourdomain.com'). The forum poster advises that this protects important transactional emails from being affected by marketing email deliverability issues.

Email marketer from Litmus shares that subdomains allow you to manage and monitor sender reputation for different email types independently. This helps in identifying and resolving deliverability issues specific to a certain type of email without affecting others.

Email marketer from Email Marketing Tips Blog explains that a good practice is to separate promotional emails to one subdomain (e.g., promo.yourdomain.com), and transactional emails to another (e.g., receipt.yourdomain.com). Separating subdomains can protect your business critical messaging.

Email marketer from Quora advises isolating different types of email traffic on different subdomains to better manage and protect email reputation. This can improve overall deliverability, as issues with one type of email won't necessarily affect others.

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.

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.

Expert from Email Geeks shares experience with clients sending high volumes (20M-80M messages a day) from one or two 5321.from subdomains, suggesting that high volume doesn't necessarily require numerous subdomains. Laura also notes that large mailers may not use subdomains the same way smaller ones do due to management complexity.

Expert from Email Geeks suggests using multiple subdomains for high-volume alerts, potentially more than three, drawing a parallel from shared IP/domain management. Al suggests that if one domain gets blocked, failing all traffic over to another could put the others at risk.

Expert from Email Geeks suggests that at 2.6 million emails per day per subdomain (with ten subdomains), the volume isn't excessive. Al mentions using sequential subdomain naming (a.domain, b.domain, etc.) and suggests aiming for recipient-recognizable branding in subdomains, such as a.alerts.domain.com over goldylocks.domain.com.

Expert from Email Geeks explains that using ten subdomains from a set of IPs will likely be seen as a shared pool and can help isolate intermittent issues with Gmail to a specific domain (1/10th of the sends) for easier troubleshooting.

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'.

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.

Documentation from RFC Editor details technical standards for email and how domains/subdomains are handled. While not explicitly stating best practices, it provides the foundational understanding that subdomains are distinct entities that can be managed separately for email sending.

Documentation from SparkPost answers that a dedicated subdomain for each type of email stream (transactional, marketing, etc.) is ideal for maintaining a good sender reputation. This way, any deliverability issues with marketing emails won't affect the delivery of critical transactional emails.

Documentation from AWS notes the best practice of separating email types by subdomains to isolate sending reputation. Transactional emails, which require higher deliverability rates, should be sent from a different subdomain than marketing or promotional emails.