Why would I manage suppression in my CRM instead of relying solely on my ESP?

While ESPs (Email Service Providers) offer basic suppression for bounces and unsubscribes, managing it in your CRM provides a centralized, holistic view of customer data across all channels. This is especially beneficial for complex segmentation, multi-ESP environments, and comprehensive compliance management.

Is manual syncing between CRM and ESP suppression lists a common requirement?

Yes, it is often necessary. If you use both a CRM and one or more ESPs, you'll need robust integrations (often via APIs) to synchronize suppression lists. This ensures that an address suppressed in one system is also suppressed in all others, preventing accidental sends and maintaining data consistency.

How do I suppress contacts who mark my emails as spam if mailbox providers don't always send complaint information?

Mailbox providers often don't provide direct feedback on spam complaints. Therefore, you need to rely on other metrics, such as engagement (opens, clicks), to identify inactive contacts and proactively suppress them from your sending lists. This helps maintain a good sender reputation even without direct complaint data.

Should soft bounces also be suppressed from my email lists?

Yes, suppressing soft bounces, especially recurring ones, is a best practice for email list hygiene. While a soft bounce is a temporary issue, repeated soft bounces can indicate an address that is effectively undeliverable and can negatively impact your sender reputation over time.

What should I do with my suppression lists when migrating to a new ESP?

When migrating to a new ESP, it's crucial to export all existing suppression lists (unsubscribes, bounces, complaints) from your old ESP and import them into your new one. You should also clean your email list of unengaged or invalid contacts before migration to ensure a fresh start and maintain good deliverability.

Should email suppression be managed in your CRM or ESP? - Sender reputation - Email deliverability - Knowledge base

Managing email suppression is a critical aspect of maintaining good sender reputation and ensuring compliance. When I first started out, I grappled with the common dilemma: should the core logic for suppressing email recipients reside within our Customer Relationship Management (CRM) system or our Email Service Provider (ESP)?

Many teams, especially those juggling multiple systems, face this exact question. The goal is to avoid sending unwanted emails, which can lead to higher spam complaints, increased bounce rates, and ultimately, damage your email deliverability. Understanding where to centralize this important function is key to efficient and effective email marketing.

The role of email suppression

Email suppression lists are essentially records of email addresses that you should not send messages to. These lists are vital for several reasons, primarily to comply with anti-spam regulations (like GDPR and CAN-SPAM) and to maintain a healthy sender reputation. If you continue to send emails to recipients who have opted out or whose addresses are no longer valid, you risk being flagged as a spammer, leading to your emails landing in the junk folder or even being blocked by internet service providers.

The addresses on a suppression list typically fall into a few categories: those who have explicitly unsubscribed, hard bounces (permanent delivery failures), and spam complaints. Some lists also include contacts who have not engaged with your emails for a long time, indicating a lack of interest.

Properly managing these lists ensures that your email campaigns are only reaching engaged recipients, which boosts your overall deliverability and the effectiveness of your marketing efforts. This is a foundational element of email list hygiene.

ESP-driven suppression

Most ESPs automatically handle a baseline level of suppression. When an email results in a hard bounce, or a recipient clicks the unsubscribe link, your ESP will automatically add that address to an internal suppression list (also known as a blocklist or blacklist). This is a core function of an ESP, ensuring that you don't continually attempt to send to invalid or opted-out addresses, which would harm your sending reputation.

While this automated process is convenient, it often isn't comprehensive enough for advanced email programs. For instance, an ESP's suppression list might not capture soft bounces that eventually become hard bounces, or it might not account for inactive subscribers who aren't explicitly unsubscribed but are harming your engagement metrics. If you're wondering how emails are suppressed after someone marks them as spam and re-subscribes, read our article why emails are suppressed after spam complaints.

Furthermore, if you use multiple ESPs (perhaps for different types of emails or as a redundancy measure), relying solely on each ESP's individual suppression list creates a fragmented view. An email address suppressed in one ESP might still be active in another, leading to inadvertent sends to unengaged or opted-out contacts. This is why some ESPs use global suppression lists for hard bounces across different customers, but this is not always sufficient.

ESP automatic suppression

Bounces and unsubscribes: Your ESP automatically adds hard bounces and explicit unsubscribes to its suppression list, which is foundational for deliverability.
Compliance: ESPs ensure basic legal compliance by preventing sends to opted-out users within their platform.
Monitoring: Most ESPs provide reports on their suppression lists, offering some visibility into deliverability issues.

CRM as the central repository

For many businesses, the CRM serves as the ultimate source of truth for customer data. It's where all interactions, preferences, and statuses are ideally consolidated. This holistic view extends naturally to email suppression. By managing suppression logic in your CRM, you can tag or segment contacts based on their email eligibility across all communication channels, not just email.

A CRM-centric approach offers greater control and a unified perspective. You can create complex suppression rules that go beyond what an ESP might offer automatically, such as suppressing customers who haven't made a purchase in a year, or those who have engaged with customer support regarding a specific issue. This allows for more granular control over who receives which emails, ensuring that you only send relevant communications.

The primary benefit of a CRM-driven strategy becomes apparent when you operate with multiple ESPs. If your CRM is the central hub for suppression, you can push updated suppression lists to all your connected ESPs, guaranteeing consistency across your entire email ecosystem. This also simplifies reporting and analysis, as all suppression data is in one place. Read our guide on how to synchronize unsubscribes when migrating ESPs.

ESP-centric management

Pros: Automated handling of bounces and unsubscribes. Simple for single-ESP setups. Ensures immediate compliance at the sending level. Prevents accidental re-engagement.
Cons: Limited visibility beyond basic events. Challenges with multiple ESPs. No unified view of customer consent or engagement outside email. Potential for redundant data and costs.

CRM-centric management

Pros: Single source of truth for all customer data. Comprehensive consent management. Facilitates complex segmentation for targeted suppression. Essential for multi-ESP environments. Improves data quality across systems.
Cons: Requires robust integration with ESPs for automated updates. Can be more complex to set up initially. Potential for data latency if sync isn't real-time. Unsubscribes might not be instant if not fully integrated.

Synchronizing data and maintaining compliance

If you decide that your CRM will be the primary source of truth for suppression logic, the challenge shifts to effective synchronization with your ESP (or multiple ESPs). This often means setting up automated data flows that regularly export suppression lists from your ESPs and import them into your CRM, and conversely, pushing suppression flags from your CRM back to your ESPs.

This synchronization can be a harsh reality for many organizations. It requires careful planning and robust integrations, often relying on APIs or custom scripts to ensure data accuracy and minimize latency. Without proper synchronization, you risk inconsistent suppression, leading to compliance issues and poor deliverability.

Maintaining compliance is paramount. GDPR, CCPA, and other data privacy regulations demand that you respect user preferences for communication. A robust suppression management strategy, whether in CRM or ESP, helps you avoid legal penalties and maintain trust with your subscribers. Learn more about what an email suppression list is and why it matters. It is also important to consider if marketers should use external preference lists for consented mail.

Proactive suppression for better deliverability

In today's email landscape, relying solely on ESP suppressions for hard bounces and unsubscribes is no longer sufficient. Mailbox providers like

Gmail and

iCloud.com do not always send back spam complaint information, meaning you might still be emailing contacts who have marked your messages as spam. To maintain a high sender reputation and good campaign performance, proactive suppression is essential.

Proactive suppression involves identifying and removing unengaged contacts from your active mailing lists even if they haven't explicitly unsubscribed or bounced. This relies on engagement metrics such as open rates, click-through rates, and recent activity. Suppressing these inactive contacts helps improve your overall email deliverability. This is why it's important to suppress soft bounces and implement other email deliverability best practices.

This responsibility extends beyond the ESP to marketers themselves. Regularly cleaning your email list (or blocklist management) is crucial, especially when migrating to a new ESP. Failing to do so can significantly impact your new provider's perception of your sending practices. For a comprehensive overview, explore an in-depth guide to email blocklists.

Suppression type	Managed by	Why it matters
Hard bounces	Primarily ESP	Essential for immediate sender reputation protection. Indicates invalid addresses.
Unsubscribes	Both ESP & CRM	Legal compliance and respecting user preferences. Avoids spam complaints.
Spam complaints	ESP-reported, CRM-tracked	Crucial for avoiding blocklists. Reduces negative signals to mailbox providers.
Unengaged contacts	Primarily CRM (marketing team)	Proactive measure to boost sender reputation and improve engagement metrics.

Views from the trenches

Best practices

Maintain a central source of truth for all suppression data, ideally within your CRM.

Implement automated synchronization between your CRM and all ESPs.

Regularly audit your suppression lists for consistency and accuracy.

Proactively suppress unengaged contacts based on defined engagement metrics.

Keep an eye on bounce and complaint rates reported by your ESPs.

Common pitfalls

Relying solely on individual ESP suppression lists, especially with multiple providers.

Manual syncing of suppression data, leading to errors and delays.

Not accounting for all types of suppression (e.g., inactive contacts, soft bounces).

Failing to integrate CRM and ESPs for a unified view of customer consent.

Ignoring mailbox provider feedback loops and complaint data.

Expert tips

Consider a phased approach to implementing CRM-driven suppression. Start with unsubscribes and hard bounces, then expand to unengaged contacts.

Utilize APIs to build robust, real-time synchronization between your CRM and ESPs.

Regularly review your email deliverability metrics and adjust your suppression strategy accordingly.

Develop clear internal processes for managing consent and suppression requests.

Remember that suppression isn't just about avoiding bad sends, it's about optimizing for engaged recipients.

Expert view

Expert from Email Geeks says: Using both the CRM and ESP for suppression is a common practice. The ESP will handle automated bounce management, and exporting that data to the CRM provides a centralized management and reporting location. However, this also complicates the removal of contacts from suppression lists, as it requires updates in both systems.

2024-08-04 - Email Geeks

Marketer view

Marketer from Email Geeks says: I suggest completely removing inactive contacts instead of just relying on ESP suppressions. There is no benefit in keeping invalid or unengaged contacts on file, especially if you are paying for them based on platform usage.

2024-08-04 - Email Geeks

Finding your balance

The decision of whether to manage email suppression in your CRM or ESP ultimately depends on your specific setup and strategic needs. For businesses with a single ESP and straightforward suppression requirements, relying primarily on the ESP's built-in suppression might suffice. However, for organizations with multiple ESPs, complex segmentation needs, or a desire for a truly unified customer view, a CRM-centric approach with robust synchronization is almost certainly the way to go.

Regardless of where you house the primary logic, the core principle remains: accurate and timely suppression is non-negotiable for email deliverability and compliance. Investing in the right processes and integrations will protect your sender reputation, keep your email campaigns effective, and ensure that your messages reach the inboxes of genuinely engaged subscribers.