How do new ESPs manage deliverability and sender reputation for large sends from non-technical small business customers?
Michael Ko
Co-founder & CEO, Suped
Published 4 May 2025
Updated 18 Aug 2025
6 min read
The challenge for new Email Service Providers (ESPs) serving small businesses is immense, particularly when managing deliverability and sender reputation for large email sends. These customers, often non-technical, frequently come from environments where they were accustomed to seamless "batch and blast" capabilities. This older model, however, can quickly jeopardize a new ESP's (and its clients') sending reputation in today's stricter email ecosystem.
The core dilemma is a kind of "chicken and egg" problem. A new ESP needs a consistent volume of email sends to build a robust sending reputation with Internet Service Providers (ISPs), but it cannot support sudden, large sends without proper IP or domain warming. Attempting to send a significant percentage of total volume to a cold list in a short time, for example, risks severe deliverability issues for everyone on the platform.
Navigating this scenario requires a delicate balance: providing a frictionless user experience while upholding stringent deliverability standards. The goal is to onboard clients smoothly and enable them to send emails effectively without inadvertently damaging the shared sending infrastructure or individual sender reputation.
Managing shared sender reputation
New ESPs often start by leveraging shared IP pools and sending domains or subdomains to manage email volume. This approach aggregates the collective reputation of all senders using those resources. While efficient for initial scaling, it introduces a significant risk, as the actions of one sender can impact the deliverability of others.
A single customer, particularly one unfamiliar with modern email marketing best practices, can inadvertently trigger spam complaints, hit spam traps, or generate high bounce rates. When this occurs, it doesn't just affect their individual campaigns. Such incidents can quickly tarnish the reputation of the entire shared IP and domain, potentially leading to widespread email blocklists (or blacklists), impacting all other customers sending through that ESP.
To mitigate these risks, new ESPs must implement robust monitoring and proactive measures. This includes real-time tracking of key engagement metrics, complaint rates, and bounces. Understanding these signals allows the ESP to identify and isolate problematic sending behaviors before they escalate and affect the entire platform's sender reputation, or worse, lead to an IP or domain blocklist.
Technical foundations and client onboarding
A fundamental aspect of achieving high email deliverability relies on proper email authentication protocols: Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication, Reporting & Conformance (DMARC). These technical records help receiving mail servers verify that an email is legitimate and authorized by the sending domain, significantly improving inbox placement and preventing spoofing.
Focus on authentication
New ESPs prioritize proper email authentication, including SPF, DKIM, and DMARC, to improve inbox placement and sender reputation. This often requires clients to configure DNS records on their domain.
Authenticating mail proves legitimacy, which is increasingly vital for trust with ISPs. Without it, even valid emails risk being flagged as spam or rejected outright.
"Batch and blast" convenience
Many small businesses are accustomed to legacy ESPs that allowed large, immediate email sends without significant technical setup, creating an expectation of frictionless sending.
This often meant clients rarely interacted with DNS settings and could send to their entire list immediately, often with less awareness of underlying reputation factors or IP warming.
The challenge for new ESPs serving small business owners, such as accountants, doctors, or lawyers, lies in the non-technical nature of these clients. Asking them to configure complex DNS records for authentication can be a significant barrier to activation and lead to frustration and churn. They often lack the technical knowledge or direct access to their DNS hosting provider's settings.
This creates a disconnect. While some older ESPs might have allowed a simpler "batch and blast" model without requiring deep technical involvement from the client, the modern email ecosystem increasingly demands proper authentication for reliable delivery. ESPs face the dilemma of pushing for necessary technical setups versus providing the seamless experience their non-technical customers expect.
Strategies for success
New ESPs must implement proactive strategies to maintain deliverability and protect sender reputation, especially given the influx of potentially unoptimized large sends from non-technical clients. This includes strict adherence to anti-spam policies, diligent list hygiene, and carefully managed sending volumes.
Key deliverability strategies
To maintain strong deliverability, new ESPs must implement a combination of best practices that go beyond basic sending. These strategies are critical for protecting sender reputation and ensuring long-term success for all clients on the platform.
Gradual warming: Implement a structured IP or domain warming plan, slowly increasing sending volume to build trust with ISPs. This is crucial for large sends to avoid blocklisting (or blacklisting).
List hygiene: Regularly clean email lists to remove inactive subscribers, bounces, and known spam traps. This improves engagement and protects sender reputation.
Segmentation: Encourage clients to segment their lists based on engagement and send targeted emails, rather than "batch and blast" to their entire list, which reduces complaints and improves deliverability.
For managing large sends, an incremental approach known as IP warming is crucial. This involves gradually increasing email volume over time to build a positive reputation with Internet Service Providers (ISPs). Even when using subdomains for individual clients, a sudden spike in volume, such as a 25,000-email send in a week, can be detrimental if not properly warmed.
Effective strategies also include educating customers on the importance of sending to engaged lists and maintaining a clean subscriber database to avoid spam traps and high bounce rates. This alignment of expectations helps prevent issues before they occur and fosters a healthier sending environment for all users on the platform. Proactive monitoring helps identify issues before they cause significant damage to sender reputation.
Empowering non-technical senders
Empowering non-technical small business customers to achieve strong deliverability requires simplifying complex technical processes. While forcing clients to configure DNS records themselves often leads to friction and churn, ESPs can offer solutions that streamline this, even for those who haven't spoken to their IT admin in years.
One effective approach involves generating CNAME records that clients can easily add to their DNS, which then point to the ESP's authentication records. Although this still requires some interaction with their DNS provider, it's generally less intimidating than setting up SPF, DKIM, and DMARC from scratch. Some tools even aim to automate this process further by integrating with common DNS hosts, though challenges remain if customers lack login details for their domain host.
Ultimately, new ESPs must invest in robust infrastructure and guidance. This includes providing clear, step-by-step instructions for DNS setup, offering strong list validation tools, and setting realistic expectations about volume ramp-up. It's a balance between making the process easy and ensuring long-term deliverability success, ultimately boosting overall email deliverability.
Conclusion
Effectively managing deliverability and sender reputation for large sends from non-technical small business customers is a complex yet critical task for new ESPs, requiring a balance between a frictionless user experience and stringent technical requirements. Success hinges on robust authentication, simplified DNS setup, and continuous education for clients on practices like list hygiene and proper warming, ultimately ensuring emails reliably reach the inbox.
By proactively addressing these areas, new ESPs can build a reliable sending infrastructure and foster long-term customer success, ensuring emails reach the inbox instead of the spam folder or encountering an email blocklist.
Views from the trenches
Best practices
Implement a strict IP/domain warming schedule to gradually build reputation, especially for new sender accounts.
Prioritize consent and list hygiene, encouraging clients to send only to engaged, opted-in subscribers.
Educate non-technical clients on the basics of email deliverability and why authentication is critical.
Common pitfalls
Allowing large, un-warmed sends from new subdomains can quickly tank sender reputation for all customers.
Overlooking the need for client-side DNS record configuration due to fear of technical friction leading to churn.
Not having clear internal processes for identifying and addressing clients who generate high spam complaints or bounces.
Expert tips
For pre-seed startups, outsourcing deliverability to established email relays can offload significant technical burden.
Consider leveraging CNAME records for authentication setup to simplify the process for non-technical clients.
Domain reputation is increasingly important, so consider pushing clients towards authenticating with their own domains.
Expert view
Expert from Email Geeks says: Email service providers in the early stages need to either outsource deliverability to dedicated email relays or be prepared to invest heavily in managing it themselves.
2025-05-27 - Email Geeks
Marketer view
Marketer from Email Geeks says: Building an all-in-one email marketing solution means handling deliverability in-house to reduce customer friction and churn, especially for non-technical clients.
