Is using different host name subdomains pointing to IPs a potential flag for email deliverability?
Summary
What email marketers say10Marketer opinions
Marketer from Email Geeks explains that using multiple domains on a single IP is acceptable because shared IP pools exist.
Email marketer from Reddit advises that using a new subdomain requires a separate warm-up process to build its reputation, even if the main domain has a good reputation. Without proper warm-up, deliverability can be negatively affected. You also have to configure SPF, DKIM, and DMARC.
Email marketer from SparkPost explains that subdomains do not automatically inherit the reputation of the parent domain. Each subdomain is treated as a separate entity by mailbox providers and requires its own warm-up and reputation building.
Email marketer from Litmus shares the value of subdomains in the context of email delivery and deliverability is that it allows a separation of traffic for specific types of emails, like marketing emails or transactional emails. This separation provides a clearer scope for sender reputation and reporting.
Email marketer from Mailjet shares that subdomains allow you to separate your email traffic (transactional, marketing) and better manage your sender reputation. Properly configured, subdomains should not negatively impact deliverability. They also recommend monitoring subdomain reputation separately.
Email marketer from Neil Patel shares that using subdomains for email marketing can help segment your audience and protect your main domain's reputation. However, it is important to properly configure the subdomain's DNS records (SPF, DKIM, DMARC) to avoid deliverability issues.
Email marketer from GlockApps shares that a new subdomain will have no sending reputation. If your main domain has a good reputation, using a subdomain will not inherit the parent's good name, so you need to warm up the subdomain.
Email marketer from StackExchange suggests that if subdomains are correctly configured with proper DNS records (SPF, DKIM, DMARC) and a good sending reputation is established, deliverability should not be negatively impacted. However, a misconfigured subdomain is likely to hurt deliverability.
Email marketer from SendPulse explains that improper setup can lead to deliverability issues. They recommend warming up the subdomain IP address to build a positive reputation, properly configure SPF, DKIM and DMARC and monitor deliverability.
Email marketer from ReturnPath emphasizes the need to monitor subdomain deliverability metrics separately. Because subdomains do not inherit domain reputation, they must be viewed as their own identity.
What the experts say5Expert opinions
Expert from Email Geeks suggests ensuring DMARC alignment requirements are relaxed when using multiple subdomains in the From header. It is acceptable but you need a good reason to do it.
Expert from Email Geeks advises having a clear, well-articulated reason for using subdomains in the From: header and re-evaluating the decision if the reason is unclear or based on misunderstandings.
Expert from SpamResource explains that using subdomains is a good way to protect your primary domains reputation. This is specifically important if your primary domain sends transactional email and your subdomains send marketing email.
Expert from Word to the Wise explains delegation of subdomains, the importance of the correct DNS delegation, and how to add records to the correct server. This helps improve deliverability.
Expert from Word to the Wise answers questions about IP and Domain Reputation, explaining IP address reputation can affect sending subdomains.
What the documentation says5Technical articles
Documentation from Microsoft warns that incorrect subdomain setup can lead to deliverability issues and emails being marked as junk. It highlights the importance of configuring SPF records to authorize sending from the subdomain.
Documentation from IETF explains the importance of PTR records for mail servers. All IP addresses used to send mail should have a valid PTR record which resolves back to the sending domain. A missing or incorrect PTR record may negatively affect deliverability.
Documentation from DMARC.org explains that DMARC alignment is crucial for deliverability when using subdomains. If the subdomain in the From: header doesn't align with the DKIM signature or SPF domain, DMARC can fail and negatively impact deliverability.
Documentation from Google explains that using subdomains for email requires setting up SPF, DKIM, and DMARC records. Failure to properly configure these records can lead to deliverability problems, including emails being marked as spam.
Documentation from RFC Editor explains that the local-part of the address (before the @) is interpreted only by the host specified in the domain part and subdomains can be used for organizational purposes without directly affecting mail routing as long as DNS records are properly configured.