Should I segregate sending IPs by recipient domain to improve email deliverability?
Summary
What email marketers say12Marketer opinions
Email marketer from Quora suggests that, for most email senders, IP segregation isn't required. It is better to focus on engaging the recipients with relevant emails.
Email marketer from StackOverflow shares that rotating IP by domain is generally a bad practice because it might look suspicious to receiver ISPs and harm the sender reputation.
Email marketer from Litmus explains the importance of maintaining a consistent sending volume and reputation across all IPs, which is more effective than segregation.
Marketer from Email Geeks explains segregating IPs is a historic spammer tactic, using IP pools of varying quality. A legitimate use case is to circumvent throttling for some country-level ISPs.
Email marketer from MailerQ suggests that IP warm up is not needed when sending to a variety of recipients and domains. The recommendation is not to segregate unless required.
Email marketer from Reddit shares that IP segregation can be helpful for very large senders or those with specific deliverability issues with certain domains, but for most, it adds unnecessary complexity.
Email marketer from Email Vendor Selection, suggests that the requirement of segregating IP is complex and usually unnecessary. Focus on segmentation, relevance, and list hygiene instead
Email marketer from Sendlane shares that IP segregation for deliverability is not necessary in modern email practice, instead it is recommended to focus on segmentation to improve deliverability.
Marketer from Email Geeks believes segregating sending IPs based on recipient domain is a waste of time because Gmail's reputation is independent of Hotmail's, even from the same IP. This might be warranted only if you're on global blacklists.
Email marketer from Mailjet Blog explains that segregating IPs per domain isn't generally recommended for small to medium senders, as it can be complex and unnecessary. Focus on good sending practices instead.
Marketer from Email Geeks suggests that if there isn't an identified deliverability problem, IP segregation isn't needed.
Email marketer from SendGrid Blog suggests that IP segregation is rarely necessary for deliverability if you're following best practices. They advise focusing on building a good reputation across all domains.
What the experts say2Expert opinions
Expert from Spam Resource explains that reputable ESPs are extremely careful about whose mail they send and that they will not usually allow IP segregation. Dedicated IP addresses are sold with the intent of a user warming up their own IP and gaining a good reputation.
Expert from Word to the Wise explains that segregating sending IPs by recipient domain (like Gmail, Yahoo, etc.) might not improve deliverability because the receiving mailbox providers look at various factors beyond just the IP address. Focus on building a good sender reputation is more important.
What the documentation says4Technical articles
Documentation from SparkPost explains that while IP pools can be segmented, it's more effective to manage sender reputation through content and engagement rather than relying solely on IP segregation by domain.
Documentation from AWS outlines dedicated IP addresses where they share that they are best suited for high-volume senders who want to manage their sender reputation independently. It doesn't directly endorse segregation by domain.
Documentation from Microsoft, using data from Hotmail and outlook services, explains that sender reputation is domain wide, and as such, IP segregation per domain is not necessary.
Documentation from RFC specifies that while technically feasible to send from different IPs to different domains, the RFC does not recommend this practice for improving deliverability.