Experts and documentation across the email industry agree that sending domains do not need to resolve to the same IP addresses as mail servers. The consensus emphasizes the paramount importance of domain authentication using SPF, DKIM, and DMARC protocols for ensuring deliverability. Reverse DNS (PTR records) for sending IPs are also vital. The advice to whitelist IPs directly without domain authentication is considered outdated and potentially confusing.
10 marketer opinions
Multiple email marketing experts and documentation sources agree that sending domains do not need to resolve to the same IP addresses as mail servers. Instead, the focus should be on proper domain authentication using SPF, DKIM, and DMARC, as these are the primary mechanisms for verifying sender identity and ensuring email deliverability. Reverse DNS (PTR records) for mail server IPs is also important.
Marketer view
Email marketer from EmailOctopus Blog shares that the sending domain is primarily used for authentication (SPF, DKIM) and reputation building. It doesn't necessarily need to resolve to the same IP as the mail server; proper authentication is more crucial.
4 Apr 2023 - EmailOctopus Blog
Marketer view
Email marketer from StackOverflow answers question clarifying that the 'sending domain' is primarily for identifying your brand, whereas SPF/DKIM records associated with your actual mail servers handle authentication. The two aren't directly linked IP-wise.
6 Feb 2025 - StackOverflow
5 expert opinions
Email deliverability experts generally agree that sending domains do not need to resolve to the same IP addresses as the mail servers sending the email. They emphasize that focusing on proper authentication mechanisms like SPF and DKIM is more crucial. One expert highlights the importance of reverse DNS (PTR records) for sending IPs. IP whitelisting is discouraged in favor of domain authentication.
Expert view
Expert from Spam Resource explains that the goal is to authenticate email communications by using SPF to publish a list of authorized IP addresses for a domain. It also says if you add multiple domains in your from header, you must make sure you include all of the parent domains in the SPF record to authenticate the email.
23 Mar 2024 - Spam Resource
Expert view
Expert from Email Geeks explains that relying on IP whitelisting leads to updating issues when IPs change. He highlights that SPF and DKIM exist to avoid IP-based sender authentication.
5 Aug 2024 - Email Geeks
5 technical articles
Email deliverability documentation consistently states that sending domains are primarily used for sender identification and authentication purposes. Resolving to the mail server's IP address is not a requirement. SPF, DKIM, and DMARC are the key technologies for verifying sender identity and domain alignment, rendering the IP address of the sending domain less critical for email deliverability.
Technical article
Documentation from DKIMProxy.org details that DKIM relies on cryptographic signatures verified against a public key published in DNS for the sending domain. It is designed to address sender authentication without requiring direct IP address correlation.
22 Oct 2022 - DKIMProxy.org
Technical article
Documentation from Microsoft Learn explains that SPF records authenticate sending sources for a domain. The focus is on authorized mail servers, not necessarily requiring the sending domain's A record to match those servers' IPs. SPF validates the sending server, not the sending domain's host IP.
7 Apr 2024 - Microsoft Learn
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