Do I need to include Mailchimp's SPF record in my domain's SPF if Mailchimp handles the bounce address?
Michael Ko
Co-founder & CEO, Suped
Published 5 Jun 2025
Updated 16 Aug 2025
7 min read
Many email senders find themselves wondering about the intricacies of SPF records, especially when using an email service provider (ESP) like Mailchimp. A common question arises: if Mailchimp handles the bounce address, do I still need to include their SPF record in my domain's SPF? This question touches upon fundamental aspects of email authentication, specifically how Sender Policy Framework (SPF) interacts with different email headers.
Understanding which domain SPF authenticates is key. SPF primarily validates the domain found in the Return-Path address, often referred to as the Mail From or RFC5321.From address. This differs from the From header (or RFC5322.From), which is the address that email recipients typically see.
When an ESP like Mailchimp sends emails on your behalf, they often use their own domain for the Return-Path address. This is done so they can handle bounces and other email feedback efficiently. Since the SPF check occurs on the Return-Path domain, it is Mailchimp's SPF record that gets checked, not necessarily yours. This crucial distinction influences whether you need to include include:servers.mcsv.net in your own domain's SPF record.
When Mailchimp handles the bounce address for the emails you send, the SPF authentication actually takes place against a Mailchimp-owned domain, such as mail236.atl61.mcsv.net. This means that the SPF record of mcsv.net is checked, not your domain's. Therefore, if your goal is solely to pass SPF for Mailchimp-sent emails, including include:servers.mcsv.net in your domain's SPF record is generally not necessary.
In fact, Mailchimp's own documentation often emphasizes setting up DKIM for domain authentication rather than SPF. They note that even with a custom Return-Path domain, Mailchimp Transactional still handles bounces. This reinforces the idea that the SPF validation happens on their side for the `Return-Path`.
So, if you look at your Mailchimp authentication settings, you'll likely find instructions for DKIM setup, which involves adding CNAME records to your DNS. This is because DKIM provides a cryptographically signed header that ties the email back to your From domain. This is generally sufficient for authenticating your domain when sending through Mailchimp, as the Return-Path is handled by their infrastructure.
Some older articles or generic advice might still suggest adding Mailchimp's SPF include to your domain. However, based on how Mailchimp manages the Return-Path address, this practice is largely outdated or stems from a misunderstanding of how SPF works with ESPs. The primary authentication for your brand's domain (the From header) when using Mailchimp should rely on DKIM.
The impact of the SPF lookup limit
A crucial aspect of SPF is the DNS lookup limit. The SPF specification (RFC 7208) mandates a limit of 10 DNS lookups for an SPF record. Exceeding this limit can cause legitimate emails to fail SPF validation, resulting in what's known as a PermError. This can negatively impact your email deliverability, pushing your emails into spam folders or leading to outright rejection.
If you have numerous services sending emails on behalf of your domain, your SPF record can quickly accumulate many include mechanisms, pushing you over the 10-lookup threshold. Adding an unnecessary include:servers.mcsv.net in this scenario only exacerbates the problem, contributing to an overly complex SPF record that is prone to failures. Many mailbox providers will treat a PermError as an SPF fail, impacting your sender reputation and deliverability.
Consider the impact of the SPF DNS timeout from Microsoft and other providers. If your SPF record is too long due to excessive lookups, it can lead to temporary errors, causing delivery delays or outright rejections. Removing unnecessary includes, like Mailchimp's, helps keep your SPF record concise and efficient, avoiding these lookup limits.
Best practices for SPF records
Minimize lookups: Aim to keep your total DNS lookups under the 10-lookup limit to prevent PermError failures.
Regularly review: Periodically check your SPF record for outdated entries or unnecessary inclusions.
SPF alignment and DMARC reports
While SPF checks the Return-Path domain, DMARC (Domain-based Message Authentication, Reporting, and Conformance) introduces the concept of alignment. For DMARC to pass via SPF, the domain in the Return-Path must align with the From domain. Since Mailchimp uses its own domain for the Return-Path, SPF will not achieve DMARC alignment for your From domain. This is a common point of confusion, especially when looking at reports from tools like Google Postmaster Tools.
In the context of DMARC, if SPF alignment fails, DKIM alignment becomes even more critical. Mailchimp enables you to set up DKIM for your sending domain, which allows the email to pass DMARC via DKIM alignment. As long as your DKIM is properly configured for your domain, your emails should achieve DMARC compliance, even if the SPF aspect for your From domain shows as Fail in DMARC reports.
The key takeaway is that for email sent through Mailchimp, your focus should be on ensuring DKIM is correctly set up for your domain. This will provide the necessary authentication for DMARC. You can read more about email authentication best practices from Mailchimp directly. While SPF is fundamental, its role in this specific scenario is often misunderstood due to the Return-Path domain being controlled by the ESP. For a simpler understanding of these protocols, check out a simple guide to DMARC, SPF, and DKIM.
Scenario: SPF 'Pass' without your include
Mailchimp sets the Return-Path (envelope sender) to their own domain (e.g., mcsv.net). The recipient server performs an SPF check against Mailchimp's domain, which passes correctly because Mailchimp authorizes its own sending IPs.
Your domain's SPF record is not involved in this SPF check, even though your domain is in the From header.
Scenario: Google Postmaster Tools shows SPF '0%'
Google Postmaster Tools reports SPF compliance for your From domain, specifically regarding SPF alignment. Since Mailchimp's Return-Path domain (Mailchimp's) does not align with your From domain, the SPF alignment for your domain fails, leading to a 0% SPF pass rate in the tool's reports.
The critical factor for DMARC success here is a passing DKIM authentication, which will align with your From domain if properly configured.
Views from the trenches
Best practices
Keep your domain's SPF record as concise as possible to avoid exceeding the 10-lookup limit.
Prioritize DKIM authentication for your sending domain, especially with ESPs like Mailchimp.
Regularly monitor your DMARC reports to understand authentication results and identify any unexpected failures.
Use subdomains for different email sending services to manage SPF records more effectively.
Common pitfalls
Including unnecessary SPF mechanisms for ESPs that handle their own bounce addresses.
Exceeding the 10-DNS lookup limit, leading to SPF PermError failures.
Misinterpreting Google Postmaster Tools SPF data when an ESP uses its own Return-Path domain.
Overlooking DKIM setup while focusing solely on SPF for authentication with ESPs.
Expert tips
Ensure your SPF record aligns with the domain in the RFC5321.From (Mail From) header.
Remember that SPF validation is for the Return-Path, not the visible From address.
Always check the actual email headers to confirm which domain SPF is checking and if it's passing.
Understand that DMARC alignment requires either SPF or DKIM to align with the From domain.
Expert view
Expert from Email Geeks says some receivers will consider SPF to have failed if you exceed the spec limits, while others may be more lenient. If you are deploying DMARC, ensuring robust DKIM is more critical.
2021-06-16 - Email Geeks
Expert view
Expert from Email Geeks says you generally do not need to add every ESP to the SPF record for your corporate domain because SPF is about authenticating the bounce address. Using custom return paths on subdomains for ESPs is a more general solution.
2021-06-16 - Email Geeks
Key takeaways for Mailchimp SPF
In summary, you typically do not need to include Mailchimp's SPF record in your domain's SPF if Mailchimp handles the bounce address. This is because SPF validates the Return-Path domain, which Mailchimp manages for bounce handling. Adding unnecessary SPF include mechanisms can lead to exceeding the 10-lookup limit, causing SPF failures and deliverability issues.
For robust email authentication with Mailchimp, focus on correctly configuring DKIM for your domain. DKIM provides a strong authentication signal that aligns with your From domain, ensuring DMARC compliance and improving your email deliverability. Always refer to the official documentation of your ESP and monitor your DMARC reports for accurate insights into your email authentication status.
By streamlining your SPF record and prioritizing DKIM, you can maintain strong email security and ensure your messages reliably reach the inbox.
Mailchimp. A common question arises: if Mailchimp handles the bounce address, do I still need to include their SPF record in my domain's SPF? This question touches upon fundamental aspects of email authentication, specifically how Sender Policy Framework (SPF) interacts with different email headers.
