What are the reasons for Return Path certification rejection and low acceptance rate?
Matthew Whittaker
Co-founder & CTO, Suped
Published 20 Jun 2025
Updated 19 Aug 2025
7 min read
For many email senders, obtaining Return Path certification has historically been seen as a gold standard for improving email deliverability. It promises a higher likelihood of reaching the inbox by signalling to mailbox providers that you are a legitimate sender. However, a common point of confusion and frustration for many applicants is the seemingly low acceptance rate. Some have reported figures as low as 4%, which can be quite surprising at first glance.
The perception of a low acceptance rate often stems from a misunderstanding of the certification process itself. It is not merely a technical checklist, but a rigorous evaluation of a sender's entire email program and reputation. Many applicants may not meet the stringent criteria from the outset, leading to what appears to be a rejection, but is often a pre-qualification assessment.
Rather than an outright rejection, it is more accurate to view many of these cases as an indication that the sender's current practices do not align with the strict standards required for certification. This article will delve into the primary reasons why senders might experience rejection or a low acceptance rate from Return Path, offering insights into the underlying factors and how to address them.
Meeting eligibility requirements
The initial assessment phase for Return Path certification involves a thorough review of an applicant's sending infrastructure and practices. This includes examining aspects like IP address usage, email acquisition methods, and engagement metrics. If an applicant's email program does not meet certain fundamental requirements, it is unlikely they will proceed far in the certification pipeline.
One of the most common reasons for not progressing is the use of shared IP addresses. Return Path typically requires senders to use dedicated IPs, which provide more control over reputation. When you use a shared IP, your sending reputation is influenced by other senders using the same IP, making it difficult to maintain the consistent, high-quality sending profile necessary for certification. This also ties into why just using a good ESP isn't enough.
Another critical factor is your subscriber acquisition strategy. Certification programs highly value clear, explicit opt-in practices. If an applicant's program relies on opt-out methods, or if their list acquisition is deemed questionable, it will likely lead to rejection. Building a healthy, engaged list is paramount.
Best practices for eligibility
Dedicated IP addresses: Ensure your email sending infrastructure uses dedicated IP addresses for your email campaigns to better control your sending reputation.
Permission-based lists: Only send to recipients who have explicitly opted in to receive your emails. Avoid purchasing lists or using opt-out programs.
Consistent volume: Maintain a consistent sending volume to build and sustain a reliable sender reputation.
Reputation hurdles and compliance issues
Even with a sound infrastructure, a sender's reputation is paramount. If your sending IP or domain is listed on a relevant blacklist (or blocklist), it is a major red flag for certification bodies. These listings indicate that your email practices have triggered spam filters or been reported by users. A low Sender Score can also be an indicator.
High complaint rates are another critical barrier. If your recipients are frequently marking your emails as spam, it signals to mailbox providers and certification programs that your content is unwanted. This can be due to irrelevant content, infrequent sending, or recipients simply not remembering opting in. Monitoring your spam rate dashboard in Postmaster Tools is essential.
Poor engagement metrics, such as low open and click-through rates, or high bounce rates, also reflect negatively on your sender reputation. These metrics suggest that your audience is not interacting with your emails, which can lead to poorer inbox placement and, consequently, make certification difficult. It is important to remember that certification aims to reward good sending behavior.
Good sending practices
Low complaint rates: Actively monitor feedback loops and remove users who complain.
High engagement: Send relevant and timely content to keep recipients engaged, leading to higher open and click rates.
Proactive list hygiene: Regularly clean your lists to remove inactive or invalid email addresses, reducing bounce rates and spam trap hits.
Bad sending practices
High complaint rates: Sending emails that recipients frequently mark as spam due to irrelevance or lack of clear consent.
Low engagement: Consistently low open or click-through rates, indicating a disengaged or unsegmented audience.
While Return Path certification primarily focuses on sender reputation and practices, underlying technical configurations are foundational to achieving good deliverability. Issues with DNS records, particularly SPF, DKIM, and DMARC, can cause emails to fail authentication checks, leading to rejection or even being marked as spam by mailbox providers. For instance, an SPF record with a soft fail can contribute to delivery problems.
A misconfigured SPF record, an invalid DKIM signature, or a DMARC policy that is too strict for your current setup can all lead to authentication failures. These failures can result in emails being rejected outright or routed to the spam folder, negatively impacting the very metrics Return Path assesses for certification. Ensuring these are properly set up is crucial for any sender, regardless of certification aspirations.
Moreover, problems like high bounce rates, especially hard bounces, indicate an unmanaged mailing list filled with invalid or non-existent email addresses. This not only wastes sending resources but also signals poor list hygiene to certification bodies. Regularly cleaning your list and using robust validation processes can significantly improve these metrics.
While not a direct rejection reason unique to Return Path, these underlying technical issues prevent senders from maintaining the stellar reputation required. It's often the case that if these technical aspects are not robust, the sender's deliverability metrics will suffer, making them ineligible for certification.
The sales funnel perspective
The seemingly low acceptance rate of Return Path certification, sometimes cited as low as 4%, might be better understood as a conversion rate from their sales funnel. Many senders inquire about certification without having the necessary foundation or current email practices that align with the strict requirements. This means a significant portion of applicants are pre-screened out before they even officially apply or get deep into the process.
Instead of an outright rejection, if an applicant has potential but their metrics are out of line, Return Path might offer a consulting engagement. This approach aims to help senders improve their email program to meet the certification standards. It's a way for them to guide legitimate businesses towards better deliverability, even if they aren't immediately certifiable.
Therefore, the low acceptance rate isn't necessarily a reflection of an overly strict barrier for qualified senders, but rather an indication of the extensive vetting process and the number of senders who simply do not meet the minimum criteria from the start. It highlights the importance of having a robust and compliant email program before pursuing certification.
Reason for low acceptance
Underlying issue
Solution/Action
Shared IP addresses
Lack of control over sending reputation; influenced by other senders.
Transition to dedicated IP addresses for your sending.
Opt-out programs/poor list acquisition
Sending to unconsenting recipients, leading to high complaints.
Implement strict, explicit opt-in processes.
High complaints/low engagement
Recipients are marking emails as spam or ignoring them.
Ensure you have a strictly opt-in email list. Purchased or scraped lists will almost certainly lead to rejection.
Maintain a consistent sending volume and good engagement rates, as these are key indicators of a healthy sending program.
Proactively monitor your IP and domain for any blacklist (or blocklist) listings and address them immediately.
Common pitfalls
Applying for certification with shared IP addresses, which dilutes your sending reputation.
Having high complaint rates or low engagement metrics, which indicate poor list quality or irrelevant content.
Not addressing underlying technical issues like improper SPF, DKIM, or DMARC configurations.
Expert tips
If your metrics are slightly off, Return Path may offer consulting services to help you improve rather than an outright rejection.
The low acceptance rate often reflects a pre-qualification process, filtering out senders who clearly don't meet basic standards.
Focus on building a strong, legitimate sending program first; certification is a recognition of these practices.
Marketer view
Marketer from Email Geeks says they haven't personally experienced a rejection but were surprised by the low publicised acceptance rate, which seemed extremely low.
2018-11-22 - Email Geeks
Marketer view
Marketer from Email Geeks says they had never heard of anyone failing to get certified, suggesting that many shady senders might be attempting to gain certification.
2018-11-22 - Email Geeks
Navigating the certification process
Achieving Return Path certification requires more than just submitting an application, it demands a commitment to excellent email sending practices. The reasons for rejection and a low acceptance rate often boil down to fundamental issues with email program health, sender reputation, and adherence to best practices. These include reliance on shared IP addresses, problematic list acquisition (like opt-out programs), high complaint rates, poor engagement, and existing blacklist (or blocklist) listings.
Understanding that the low acceptance rate reflects a stringent initial vetting process rather than an arbitrary rejection can help put things into perspective. For senders serious about improving their email deliverability, the focus should always be on building and maintaining a clean, engaged, and compliant email program first. This foundational work is what ultimately leads to higher inbox placement, whether through certification or simply by being a responsible sender.
Actively monitor feedback loops and remove users who complain.
