What are the primary responsibilities of an ESP regarding deliverability?

The main responsibility of an ESP is to provide the underlying technical infrastructure for sending emails. This includes maintaining email servers, managing IP addresses, ensuring network connectivity, and handling core email authentication mechanisms like SPF, DKIM, and DMARC. They also often manage their IP reputation with ISPs.

What key deliverability responsibilities fall on the business (sender)?

Businesses are responsible for the content of their emails, the quality of their recipient lists, and overall sender reputation. This includes obtaining proper consent, maintaining list hygiene , monitoring engagement (opens, clicks, complaints), and ensuring their emails provide value to subscribers. These factors significantly influence how ISPs perceive the sender.

Can a business still have deliverability issues even with a good ESP?

Yes, even with a great ESP, poor sending practices by a business can negatively impact deliverability. An ESP provides the vehicle, but the driver (the business) controls where it goes and how safely. Sending to unengaged lists, generating high spam complaints, or sending irrelevant content can damage the business's sender reputation, leading to emails being blocked or landing in the spam folder, regardless of the ESP's technical setup. This is true whether you use dedicated or shared IPs .

What is the typical percentage split of deliverability responsibility?

The division is often considered to be around 80-90% on the business and 10-20% on the ESP . While the ESP ensures technical infrastructure and basic compliance, the vast majority of factors influencing inbox placement, such as list quality, content relevance, and recipient engagement, are controlled by the business.

What is the division of email deliverability responsibility between ESPs and businesses? - Basics - Email deliverability - Knowledge base

When a business sends emails through an Email Service Provider (ESP), a common question arises: Who is truly responsible for email deliverability? Is it the ESP's job to ensure every email lands in the inbox, or does the business bear the primary burden? Many businesses often assume their ESP handles all aspects of deliverability, leading to misunderstandings and potential inbox placement issues.

The reality is that email deliverability is a shared responsibility. While an ESP provides the critical infrastructure and technical framework, the success of email campaigns ultimately depends heavily on the sender's practices. It is a partnership where both parties have distinct, yet interconnected, roles.

Understanding this division of labor is crucial for any business relying on email to reach its audience. My goal here is to demystify these roles and provide clarity on what each party brings to the table in the intricate world of email delivery.

The ESP's realm: infrastructure and technical foundation

ESPs are the backbone of modern email communication, handling the complex technical aspects that ensure your emails can even attempt to reach recipients. This includes managing sending IP addresses, maintaining server infrastructure, and ensuring proper connectivity with Internet Service Providers (ISPs).

A key part of their role involves setting up and managing email authentication protocols like SPF, DKIM, and DMARC. These records verify your domain's legitimacy and protect against spoofing, which is fundamental for good deliverability. Most ESPs handle the intricate details of these DNS records, though the business usually needs to add specific entries to their domain's DNS.

Example SPF recordDNS

v=spf1 include:_spf.example.com include:esp.com ~all

ESPs also play a crucial role in managing IP reputation, particularly when using shared IP pools. They monitor for blacklistings (or blocklistings) and often have relationships with ISPs to resolve delivery issues stemming from their infrastructure. This includes actively managing their network to prevent abuse, which is essential to keeping their shared IP space clean for all clients.

The business's domain: content, list, and engagement

While ESPs handle the technical plumbing, the business (the sender) is primarily responsible for the content, audience, and overall sending practices. This aspect profoundly impacts whether an email lands in the inbox or the spam folder. It’s about building and maintaining a positive sender reputation with ISPs, which is largely influenced by subscriber engagement.

Key responsibilities include maintaining a clean and engaged email list, avoiding spam traps, and regularly removing unengaged subscribers. The content of your emails also matters immensely, including relevance, personalization, and avoiding spammy keywords or link shorteners. High complaint rates or low engagement rates directly signal to ISPs that your emails might not be wanted, regardless of how technically sound your ESP is.

Even with an ESP providing robust authentication and infrastructure, the business is ultimately accountable for adherence to email marketing best practices and legal compliance. This includes honoring unsubscribe requests promptly and ensuring clear consent for all subscribers. Your brand's reputation, built through consistent, valued communication, is the most significant factor in long-term deliverability success.

The intertwined nature of shared deliverability

While distinct, the responsibilities of ESPs and businesses are deeply intertwined. A business's poor sending habits, such as sending to unengaged lists or generating high spam complaints, can negatively impact an ESP's shared IP reputation. Conversely, an ESP with weak abuse prevention or outdated technical configurations can harm even the most diligent sender.

This symbiosis means that effective email deliverability requires ongoing collaboration and transparent communication. ESPs often provide tools and analytics to help businesses monitor their performance, such as bounce rates and complaint metrics. Businesses should actively use these insights to refine their sending strategy and address issues proactively.

Core technical duties

IP & infrastructure management: Overseeing IP addresses, server health, and network stability to facilitate sending.
Email authentication: Setting up and maintaining SPF, DKIM, and DMARC records for sender verification.
Abuse desk operations: Handling complaints and ensuring their shared IP reputation remains high.
ISP relationships: Building and maintaining connections with mailbox providers like Gmail and Yahoo.

Sender behavior and content

List hygiene & segmentation: Ensuring lists are clean, removing invalid or inactive addresses.
Content quality & relevance: Crafting engaging and non-spammy email content.
Engagement metrics: Monitoring opens, clicks, unsubscribes, and spam complaints.
Subscriber consent: Obtaining explicit permission before adding recipients to mailing lists.

A good ESP will provide the necessary tools and guidance, but the ultimate application of these tools and adherence to best practices rests with the business. It’s like a car manufacturer providing a reliable vehicle, but the driver is responsible for safe operation on the road. For example, even if an ESP manages dedicated IPs, the sender's actions directly influence the reputation of those IPs.

Navigating the balance of accountability

There's often debate about the exact percentage split of responsibility. Some argue it's closer to 50/50, while others suggest the business holds 90% or more of the accountability. My experience indicates that while the ESP provides essential infrastructure (which they generally do well if they are reputable), the business's sending behavior, list quality, and content strategy are by far the dominant factors influencing inbox placement.

An ESP that fails to manage its network or provides poor infrastructure can indeed cause deliverability issues for its clients. However, even the best ESP cannot overcome consistently bad sending practices from a business, like sending to purchased lists or having excessively high complaint rates. The onus is on the business to understand that their sender reputation is largely in their hands, regardless of the ESP they use. Spamhaus, for instance, has been known to blacklist entire ESPs if systemic issues are present.

Proactive steps for optimal deliverability

To achieve optimal deliverability, businesses must take a proactive stance. This involves regular list cleaning, monitoring engagement metrics, personalizing content, and adhering to strict consent policies. Relying solely on the ESP for deliverability without active involvement from the business side is a common pitfall that often leads to emails landing in the spam folder (or junk folders). Deliverability is a journey, not a destination, requiring continuous attention from both the ESP and the sender.

Views from the trenches

Best practices

Actively monitor your sender reputation and engagement metrics through your ESP's provided tools.

Segment your audience based on engagement and send targeted, relevant content to different groups.

Implement a strict list hygiene routine, removing inactive or invalid addresses regularly.

Ensure all email authentication (SPF, DKIM, DMARC) records are correctly configured and monitored.

Common pitfalls

Assuming the ESP is solely responsible for all deliverability outcomes and issues.

Sending to old, unengaged, or purchased email lists, leading to high bounce and complaint rates.

Ignoring feedback loops and performance reports provided by the ESP.

Failing to adapt email content and sending frequency based on subscriber behavior.

Expert tips

Understand that technical setup is only one part, and content relevance drives true inbox placement.

Always honor unsubscribe requests immediately and ensure clear consent for all subscribers.

Even with a dedicated IP, your sending behavior dictates its reputation.

Proactively police your email lists and sending practices to prevent network-wide blocklistings.

Expert view

Expert from Email Geeks says the ESP primarily handles infrastructure, like SPF and DKIM setup, and timely email dispatch. However, the business is responsible for content and audience selection, which are crucial for reputation.

2019-10-04 - Email Geeks

Marketer view

Marketer from Email Geeks says that the vast majority, at least 90%, of deliverability responsibility lies with the company, as even authentication protocols require correct incorporation by the sender.

2019-10-04 - Email Geeks

The path to inbox success: A shared journey

Email deliverability is a partnership between the Email Service Provider and the business (sender). While ESPs provide the essential technical infrastructure, including robust sending servers and authentication protocols, businesses hold significant responsibility for their sending practices.

Ultimately, the success of your email campaigns, particularly their inbox placement, hinges on a harmonious balance between the ESP's technical capabilities and the business's commitment to ethical and engaging email marketing. Both parties must actively contribute and collaborate to ensure messages consistently reach their intended recipients.