How do ESPs impact deliverability on dedicated IPs?

Key findings

1. Infrastructure Quality: The underlying sending engine and server configurations of an ESP can significantly affect how emails are processed and delivered. Not all sending platforms are built with the same level of sophistication in handling issues like misspelled domains or optimizing mail transfer agent (MTA) settings.
2. Automated Deliverability Tools: ESPs often provide features like auto-warming for new IPs, bounce management, and robust list hygiene tools. These automated functions are crucial for maintaining a healthy sending reputation on a dedicated IP. For instance, an ESP should automatically enroll in feedback loops and process unsubscribe requests and complaints efficiently.
3. Policing and Reputation Management: While a dedicated IP means direct control, the ESP's policies regarding IP recycling and handling of problematic clients (even on dedicated IPs) are vital. A good ESP will implement a cooling-off period for IPs and prevent bad actors from immediately inheriting a previously burned reputation.
4. Technical Compliance and Standards: ESPs are responsible for keeping up with evolving email standards and technical compliance, such as proper authentication management (SPF, DKIM, DMARC) and correctly implementing headers like List-Unsubscribe, which impacts email deliverability and sender reputation.

Key considerations

1. Sales Claims vs. Reality: Be wary of ESPs that simply claim to have great deliverability. On a dedicated IP, much of the responsibility falls on the sender. A good ESP will emphasize their support, proactive mitigation, and best practice guidance rather than making broad claims about inherent deliverability.
2. Beyond Warm-up: While warm-up assistance is crucial during onboarding (see IP warming strategies), a long-term relationship with an ESP on a dedicated IP should focus on ongoing support, consultation, and platform features that maintain deliverability, even after the initial warming phase.
3. Throttling and Rate Limiting: An ESP's ability to configure and manage email throttling (spreading out sends) is important for maintaining optimal deliverability, especially when sending large volumes or facing temporary ISP restrictions.
4. Proactive Monitoring and Support: A valuable ESP provides ongoing monitoring of network deliverability, offers consultation packages, and helps identify potential issues before they escalate, even if these are upsells. This proactive approach helps to prevent emails from going to spam.

Key opinions

1. Backend Systems Matter: Marketers emphasize that the quality of an ESP's sending engine is crucial. Some engines prevent sending to misspelled domains, while others might not, directly impacting bounces and list quality.
2. Hidden Technical Issues: ESPs must stay updated with email standards, such as implementing the correct List-Unsubscribe headers. Outdated or incorrect implementations can lead to unintended unsubscribes or deliverability issues, even on a dedicated IP.
3. Automated Hygiene and Management: Features like bounce management, spam trap suppression, and processing feedback loops are vital ESP functions that directly support a sender's deliverability efforts on a dedicated IP. This also includes setting up whitelabeling if not automated.
4. Ongoing Support and Policy: The ESP's role extends to providing competent assistance, offering visibility into trends, and enforcing policies that prevent clients from engaging in practices that could harm the dedicated IP's reputation, even if that means acting as the bad guy to management.

Key considerations

1. Beyond Initial Warm-up: While onboarding assistance is a selling point, marketers should consider the ESP's role beyond the initial warming phase, focusing on long-term deliverability maintenance.
2. Throttling Configurations: The ability to configure throttling at the VMTA (Virtual Mail Transfer Agent) level allows senders to manage the pace of their sends, making them more digestible for receiving ISPs and helping to maintain a healthy sender reputation.
3. ISP Relationships: A good ESP will have established relationships with ISPs (Internet Service Providers), which can be beneficial in resolving deliverability issues, even for clients on dedicated IPs.
4. Value Proposition: Marketers should question ESPs that make grand claims about great deliverability on dedicated IPs, as the sender's practices are paramount. The ESP's true value lies in robust backend support and expert guidance. For more on this, consider resources like Mailchimp's guide on dedicated IP benefits.

Key opinions

1. Comprehensive Deliverability Functions: Experts highlight that ESPs handle essential tasks like bounce management, list hygiene (trap and typo suppression), network-wide deliverability monitoring, and blocklist mitigation. These are continuous efforts that contribute to the dedicated IP's health.
2. Technical Advancement: A good ESP keeps pace with new email technologies, monitors rate limits, and performs authentication monitoring. This proactive approach ensures that the sending infrastructure remains aligned with ISP requirements and prevents deliverability degradation.
3. Infrastructure Tuning: ESPs provide a tuned infrastructure that can handle large sending volumes, considering factors like per-hour message limits. While customers dictate overall volume, the ESP optimizes the technical setup for efficient delivery. This helps avoid issues that might lead to a blocklist event.
4. Strategic Partnership: Experts emphasize the ESP's role in providing strategic guidance and policy enforcement. They can advise clients on best practices and even intervene to prevent actions that could harm deliverability, serving as a valuable internal ally for senders.

Key considerations

1. IP Policing and Recycling: A critical ESP function is ensuring proper management and recycling of dedicated IPs. Experts recommend a 30-90 day cooling-off period before reassigning IPs to new clients to prevent inherited bad reputations, which can lead to emails going to spam.
2. Ongoing Consultation: ESPs offer deliverability consultation packages, which can include regular reports and calls, helping clients brainstorm how changes might impact future deliverability and address issues proactively. This is especially useful for understanding factors influencing domain reputation.
3. Efficiency of Scale: ESPs bring efficiency of scale in data analysis and bounce management rules. This centralized expertise and tooling are difficult for individual senders to replicate effectively.
4. Distinguishing ESP Claims: As noted by Word to the Wise, ESPs that claim superior deliverability often refer to their own internal processes rather than a magic bullet for clients' dedicated IPs. Senders should look for ESPs that provide robust tools and support for the client's own deliverability efforts.

Key findings

1. Core Infrastructure Provision: ESPs provide and maintain the server infrastructure (like MTAs) necessary for sending emails. This includes ensuring high uptime and optimizing configurations for efficient mail flow.
2. Technical Compliance and Automation: Documentation confirms that ESPs automate critical functions such as processing unsubscribe requests, managing bounces, and handling feedback loops (FBLs). They also ensure proper implementation of email authentication standards like SPF, DKIM, and DMARC. See Mailgun's cheat sheet for more.
3. Reputation Management Support: While sender reputation is primarily linked to the dedicated IP's user, ESPs offer tools and guidance for IP warming, monitoring, and proactive issue resolution, which indirectly supports the dedicated IP's standing.
4. Security and Abuse Prevention: ESPs are responsible for preventing their platform from being used for malicious activities (spam, phishing). Their internal policing and abuse prevention mechanisms help maintain a clean ecosystem, which can impact the perception of IPs hosted on their network.

Key considerations

1. Shared Responsibility: Documentation often implies a shared responsibility model, where the ESP provides the reliable platform, and the sender is responsible for content quality, list hygiene, and sending practices on their dedicated IP. Irregularities in sending behavior can still impact deliverability, even with a dedicated IP.
2. IP Assignment and Lifecycle: ESPs manage the lifecycle of IP addresses, including their provisioning and potential recycling. The quality of this management (e.g., ensuring a cooling-off period for IPs) can affect a new client's starting reputation. This aligns with concerns about reputation transfer during IP warming.
3. Customer Support and Consultation: While not directly about deliverability, the availability of expert customer support and deliverability consultation services is a key offering from ESPs that indirectly impacts a dedicated IP sender's success.
4. Adaptability to ISP Changes: ESPs continuously adapt their systems to changes in ISP filtering rules and requirements, offloading this burden from individual senders. This ensures that the technical aspects of sending remain compliant over time.