What are the biggest gripes about deliverability services offered by ESPs?
Matthew Whittaker
Co-founder & CTO, Suped
Published 21 Jul 2025
Updated 17 Aug 2025
7 min read
Email Service Providers (ESPs) are the backbone of many email marketing and transactional email operations. They offer various tools and services designed to streamline email campaigns, manage subscriber lists, and crucially, aid in email deliverability. While these services are indispensable, many users encounter frustrations with the limitations or opaque nature of deliverability features. These gripes often revolve around a lack of granular data, insufficient control over critical authentication protocols, and the quality of expert support provided.
Understanding these common points of friction is key to improving the overall email sending experience and achieving better inbox placement. It highlights the areas where senders need to be more proactive in managing their own deliverability, rather than solely relying on their ESP's offerings.
Lack of transparency and data access
One of the most persistent complaints centers on the limited access to raw, unfiltered data. Many ESPs provide aggregated metrics like 'hard bounce' and 'soft bounce' without offering the underlying Simple Mail Transfer Protocol (SMTP) responses. This lack of detail makes it incredibly difficult to diagnose specific deliverability issues, leaving senders to guess at the root cause of problems.
When emails fail to deliver, the actual bounce message often contains vital clues about why a mailbox provider (MP) rejected the email. Without this crucial information, troubleshooting becomes a tedious and often ineffective process. Senders are left with a high-level summary, which is rarely enough to implement precise corrective actions or understand complex filtering decisions by ISPs.
Furthermore, some ESPs are accused of silently altering or filtering data before presenting it to customers. This can include masking certain bounce codes or omitting details that might indicate issues with their own infrastructure or shared IP pools. This obfuscation prevents senders from truly understanding their email performance and making informed decisions.
The inability to download raw bounce logs or detailed delivery reports in an easily digestible format, such as a CSV, forces power users to spend countless hours manually piecing together clues. This significantly impedes their ability to quickly identify and resolve deliverability challenges.
The need for raw data access
To effectively troubleshoot and improve email deliverability, senders need access to raw SMTP responses. These codes provide specific reasons for email rejection or deferral, such as invalid recipients, full mailboxes, or content-based filtering. Understanding these granular details allows for targeted adjustments to sending practices or list hygiene, which ESPs often abstract away.
Without transparent data, it's challenging to accurately assess your sender reputation or identify if your domain is on a blacklist (or blocklist). A lack of visibility into these critical factors can lead to ongoing deliverability issues that are difficult to pinpoint and resolve.
Limited control over authentication and infrastructure
Email authentication protocols like SPF, DKIM, and DMARC are fundamental to email deliverability. However, a common frustration for senders is the limited flexibility ESPs offer in managing these critical DNS records. Many ESPs push for CNAME-based DKIM setups, which, while simpler for some users, can restrict the sender's ability to use their own DKIM keys or fully control their authentication. This often leads to issues during IP and subdomain warmup after an ESP migration.
The imposition of certain authentication schemes can hinder a sender's desire for full control over their email identity. For instance, if an ESP doesn't support custom DKIM configurations, it might force senders into a less optimal setup that impacts their deliverability or brand visibility, especially if they are looking for specific ESP capabilities related to email authentication.
This limited control can also affect how a sender manages their DMARC policy. While many ESPs handle the basics, advanced DMARC configurations often require direct DNS access and a deep understanding of how to implement it correctly. Senders might find their ESP's interface or support inadequate for these more complex needs.
The shared responsibility for email delivery is a well-known concept, but the exact division of responsibility is often unclear or misrepresented. As Spamhaus notes, deliverability is a partnership. However, many senders feel that ESPs overstate their role in ensuring inbox placement, leading to unrealistic expectations.
ESP's perspective
Simplified Setup: ESPs often default to CNAME records for DKIM, making setup easier for less technical users. This abstracts away complex DNS management.
Shared Reputation Management: ESPs manage shared IP pools and a collective sender reputation. They might limit custom key usage to maintain control and prevent abuse that could impact other clients.
Sender's perspective
Full Control: Senders (especially larger enterprises) prefer to use their own DKIM keys for enhanced security, brand consistency, and better control over their authentication records across multiple sending platforms.
Troubleshooting Complexity: When issues like a DKIM record not found occur, proprietary CNAME setups can make diagnosis more difficult than a direct DKIM record.
Inadequate support and misleading information
The quality of support and advice from ESP deliverability teams can be a significant point of contention. Some senders report that ESP support staff, despite being well-meaning, may lack adequate training in the nuances of email deliverability. This can lead to generic or even incorrect advice, often described as cargo culting advice, where solutions are applied without a deep understanding of the underlying problem.
This issue extends to the content marketing efforts of some ESPs. Articles and guides on deliverability might be written by general marketers who Google information without critically evaluating its accuracy or relevance in the ever-evolving email landscape. This can perpetuate misinformation, making it harder for senders to find reliable advice and improve their deliverability.
When deliverability problems arise, senders often seek expert guidance. If the ESP's internal deliverability team is understaffed, undertrained, or relies heavily on AI-generated content without human oversight, the quality of support suffers. This can lead to prolonged deliverability issues, impacting campaign performance and sender reputation.
Impact on sender reputation and inbox placement
Despite ESPs often touting high delivery rates, the reality of inbox placement can be quite different. Many senders report that their emails frequently land in the spam folder, even when their campaigns adhere to best practices. This disparity can stem from the ESP's own sender reputation, particularly if they manage shared IP pools with other clients who might be engaging in questionable sending behavior.
A key grievance is when an ESP's shared IP address or domain gets listed on a public blocklist (or blacklist). When this happens, all clients using that shared resource can experience significant deliverability issues, even if their own sending practices are exemplary. As Word to the Wise highlights, an ESP's reputation directly impacts its customers.
While ESPs have an incentive to maintain good reputations, the sheer volume of mail they send and the varying quality of their client base can make this challenging. Senders often feel powerless when their deliverability is impacted by factors beyond their control, such as a problematic neighbor on a shared IP.
This often leads senders to question the efficacy of their email deliverability and whether they are getting the true inbox placement rates rather than just delivery rates. It underscores the importance of a comprehensive strategy that goes beyond basic ESP features.
Views from the trenches
Best practices
Always seek raw SMTP responses or detailed bounce logs for comprehensive troubleshooting.
Prioritize ESPs that offer transparent reporting and allow flexibility in managing authentication records.
Invest in internal knowledge or external consultants to complement your ESP's deliverability support.
Common pitfalls
Relying solely on high-level bounce categorizations from your ESP without understanding underlying issues.
Accepting default CNAME-based DKIM setups without considering custom key options for better control.
Assuming your ESP's content marketing or support staff provide universally accurate deliverability advice.
Expert tips
A proactive approach to deliverability, combined with independent data analysis, empowers senders.
Understanding the nuances of DMARC and DKIM alignment is crucial, regardless of ESP configurations.
Regularly audit your email list for invalid addresses to reduce bounces and maintain a healthy sender reputation.
Marketer view
Marketer from Email Geeks says they find it difficult to use their own DKIM keys instead of the CNAME scheme ESPs try to force on them.
2024-01-17 - Email Geeks
Marketer view
Marketer from Email Geeks says a major gripe is having no access to raw SMTP responses, forcing reliance on only "Hard Bounce" and "Soft Bounce" classifications.
2024-01-17 - Email Geeks
Navigating the deliverability landscape
While Email Service Providers are essential partners in the email ecosystem, it's clear that many senders grapple with frustrations related to their deliverability services. The desire for greater transparency in data reporting, more granular control over authentication mechanisms like DMARC, SPF, and DKIM, and higher quality, accurate support are common themes.
These gripes highlight a crucial gap between what senders need to achieve optimal inbox placement and what many ESPs currently offer. For businesses heavily reliant on email, understanding these limitations is the first step toward implementing a more robust deliverability strategy.
Ultimately, successful email deliverability requires a collaborative effort. While ESPs provide the sending infrastructure, senders must take ownership of their sender reputation, list hygiene, and a deep understanding of email authentication to truly maximize their inbox reach. Supplementing ESP services with independent monitoring and expertise can significantly mitigate these common frustrations.
