What steps should I take to improve email deliverability with a large, unengaged contact list and high bounce rates?

Key findings

• List quality is paramount: A significant percentage of unengaged contacts and high bounce rates indicate a fundamental problem with your email list quality. Purchased or outdated lists are major contributors to poor deliverability.
• Sender reputation is at risk: High bounce rates directly harm your sender reputation, leading to more emails landing in spam folders or being blocked entirely. This applies to both IP and domain reputation.
• Engagement signals matter: Mailbox providers heavily weigh engagement (opens, clicks) when deciding where to place your emails. A high percentage of unengaged contacts signals low interest, negatively impacting deliverability.
• Cross-departmental challenge: Multiple business lines using the same sending account, especially if some are adding poor-quality data, can quickly degrade the shared sender reputation for everyone.

Key considerations

• Prioritize list cleaning: Aggressively remove invalid and unengaged contacts. This is often the most impactful first step. Regular email verification is essential.
• Implement strict opt-in policies: Move towards double opt-in for all new subscribers to ensure explicit consent and higher engagement. This helps prevent future list contamination.
• Segment and re-engage cautiously: For existing unengaged segments, consider a targeted re-engagement strategy or sunsetting them. Sending to a highly unengaged audience will only perpetuate deliverability issues. More on this topic can be found in a guide on enhancing email deliverability.
• Educate and enforce: Establish clear email sending policies across all business units and educate stakeholders on the impact of poor list practices.

Key opinions

• Prioritize data quality: The most significant impact comes from stopping the inflow of bad data, particularly purchased lists. Once new, poor data is prevented, existing data can be cleaned.
• Analyze bounce codes: Checking suppression and block lists and analyzing bounce error codes is crucial for identifying specific issues and problematic mailbox providers.
• Respect opt-outs: Ensuring opt-outs are honored and that there are no CAN-SPAM violations is fundamental to maintaining a good sending reputation.
• Separate business lines: For long-term sustainability, it is advisable to strategize separating business lines across different accounts or sub-accounts to prevent one bad actor from affecting others.

Key considerations

• Policy enforcement is key: Gaining management backing to set and enforce clear email sending policies is vital for long-term success. This can be challenging but is necessary to prevent recurring issues, as highlighted in how to persuade management.
• Suppress problematic addresses: Temporarily suppressing or permanently removing known purchased or unengaged addresses is a practical step to stem immediate deliverability bleeding.
• Long-term effort: Rebuilding data and reputation is a multi-month job, requiring patience and consistent effort. Expect small, incremental improvements rather than overnight fixes.
• Leverage engagement data: Utilize open and click data to identify active subscribers. Suppressing those who have never engaged can be a beneficial step to improve overall list health and prevent higher bounce rates.

Key opinions

• DMARC reports are not for initial diagnosis: While useful for authentication, DMARC monitoring reports won't provide the most immediate or insightful data for severe deliverability problems stemming from poor list quality and high bounces.
• Focus on rejection rates: The primary source of diagnostic data should be rejection rates (bounces), ideally broken down by list source and recipient domain. This reveals where bad addresses originate and where blocks are occurring.
• Leverage engagement data: Image load data (opens) and click data provide valuable insights into recipient interaction. Suppressing non-engagers can help improve sender reputation.
• Strategic engagement with stakeholders: Having relaxed conversations with email leads in each business line can provide context for metrics and identify which areas require the most attention regarding email practices.

Key considerations

• Verify with Postmaster Tools: Verify your sending domain with Google Postmaster Tools and Microsoft SNDS (Sender Network Data Services). These are critical for B2C lists and provide insights into how major mailbox providers view your sending streams.
• Control the chaos: Gather data from your ESP (e.g., SendGrid metrics, blocks, bounces, engagement, domain reputation) to build a compelling case for management to halt problematic sending practices.
• Segment mailstreams: Consider separating mailstreams into different child accounts within your ESP to isolate issues and protect the overall sender reputation. This is particularly relevant when dealing with sending to large, unengaged lists with no existing reputation.
• Seek ESP assistance: Many ESPs, like SendGrid, offer deliverability services and expertise. Leveraging their support can provide significant guidance during complex recovery efforts. Twilio's blog also covers best practices for email deliverability.

Key findings

• Authentication is foundational: Proper implementation of SPF, DKIM, and DMARC is essential for proving sender legitimacy and preventing spoofing. This directly impacts how mailbox providers trust your emails.
• Consent is critical: Only sending to recipients who have explicitly opted in (ideally via double opt-in) is a universal best practice to minimize complaints and spam trap hits.
• Regular list hygiene: Documentation consistently recommends regular removal of invalid, inactive, and bounced addresses to maintain list health and improve sender reputation metrics.
• Monitoring sender reputation: Tools like Google Postmaster Tools and Microsoft SNDS are provided by ISPs to give senders insights into their sending reputation, spam rates, and deliverability performance directly from the source.

Key considerations

• Adhere to sending limits: ESPs and mailbox providers often have sending limits or throttling recommendations. Sending too many emails too quickly, especially to a poor-quality list, can trigger spam filters and lead to blocks.
• Understand bounce types: Distinguish between hard and soft bounces. Hard bounces should be removed immediately. Understanding how bounces impact deliverability is vital.
• Monitor blocklists: Regularly check if your sending IP or domain is listed on any public blocklists. Prompt action is needed if you find yourself on a blacklist. Our guide to email blocklists provides further detail.
• Implement DMARC: While not a magic bullet, DMARC provides crucial feedback reports (RUA and RUF) that help identify authentication failures and potential abuse of your domain. A comprehensive guide on DMARC highlights its benefits.