I have three BU all using the same domain to send mails from.
- news@mail.example.com

But each BU has its own dedicated IP address.
For example:
BU1 -
BU2 -
BU3 -

Will they have a combined reputation (because of the shared domain), and will they influence each other?

Or is the reputation calculated completely separated because of the shared IP's?

If I want to separate the domain and the IP address, but keep the current IP addresses, do I have to redo the warm-up process?
For example:
BU1 - - news@mail.example.com
BU2 - - news@mail.example.com
BU3 - - news@mail.example.com

New set-up:
BU1 - - news@news.example.com
BU2 - - offers@offers.example.com
BU3 - - notifications@notifications.example.com

Same IP addresses are used as in the current set-up, but now also with separated domains. Need to re-warmup?


There is no conclusive answer to your question. IP addresses will still be leading, when it comes to reputation - which has been the historical behaviour with mailbox providers. More recently, domains have been taken more into consideration, especially with Gmail. However no major mailbox providers are sharing details on how the exact sender reputation is calculated.

With the adoption of IPv6, there are now exponentially more IP addresses available. This growth makes IP address reputation much more difficult for the mailbox providers to effectively monitor. To help deal with this added volume, mailbox providers are leaning towards more domain-based authentication for their filtering decisions, as this is a more manageable way for them to monitor a sender’s reputation.

Looking at authenticated domains to track and determine a sender’s reputation also allows mailbox providers to more easily see email traffic across multiple IP addresses and identify legitimate versus spoofed emails. This allows mailbox providers to get a more accurate reputation picture of a sender.

If you want to be entirely sure to have and fully separated reputation, separating both domains and IP address is the way forward. Do observe, that some mailbox providers also look across multiple subdomains to calculate your reputation, e.g. marketing.example.com, offers.example.com, and in some cases example.com will influence each other.

As in your example, you will be using different sender email address, but on same domain - hence an IP warmup is not needed at all.

  • I didn’t get your question. Can you please explain what do you mean by “separating domain and IP and keeping current IP”? – Lukas Lunow Feb 16 '20 at 9:24
  • See the edit in my original question :), Do I need to follow the warm up process again after separating the domains, but keeping the current IP's. – user6079228 Feb 16 '20 at 9:32
  • 1
    You will not need IP warmup, as you still send from same domain. See my updated reply. – Lukas Lunow Feb 16 '20 at 10:19
  • Thx, And if i would change the domains 'after the @'? Like news@news.example.com, offers@offers.example.com. Warm-up needed? – user6079228 Feb 16 '20 at 10:27
  • Also no - especially since you still will be using same top domain (example.com) – Lukas Lunow Feb 16 '20 at 10:35

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