Why are 250ok seed lists showing missing emails and how to fix?

Key findings

• Technical not reputation: The "missing" category in 250ok reports typically indicates a technical sending problem, not a reputation issue.
• Suppression: Emails might be suppressed post-deployment by your sending system.
• Reference addresses: Only a subset of seed list addresses (often called "reference addresses") may be receiving the mail.
• Engagement rules: Seed addresses do not engage, so they can be filtered out by engagement-based suppression or segmentation rules within your ESP.

Key considerations

• Review ESP suppression: It is essential to check your Email Service Provider's (ESP) suppression lists or tables for these addresses, even if they are subscribed.
• Isolate seed lists: Consider isolating your seed list into a separate segment that bypasses engagement-based filters. Learn more about testing your deliverability using seedlists and DMARC configurations.
• Engagement logic: If your campaign segments are based on engagement (e.g., opens or clicks), seed addresses will be automatically excluded.
• X-header implementation: Although ruled out in some cases, ensure unique x-headers are properly implemented for tracking purposes. This helps monitor inbox placement for your emails.
• Time-based issues: Be aware of any time-based suppression rules that might affect seeds, as their lack of activity can trigger these.
• Seed list accuracy: Understand how accurate are seed lists for email deliverability testing.

Key opinions

• Campaign segmentation: Marketers find that seed lists are frequently excluded by automated segmentation due to lack of opens or clicks.
• Dedicated lists: Many suggest maintaining separate, non-suppressed lists specifically for seed addresses to ensure they receive emails.
• Re-engagement campaigns: If non-engaged addresses are removed post-re-engagement campaigns, seeds will be affected.
• Automated suppression: Automated suppression time periods are a common cause of missing seeds.

Key considerations

• Review ESP settings: Marketers should thoroughly check their ESP's settings for any suppression rules that might unintentionally exclude seed addresses. Follow email deliverability best practices.
• Seed list isolation: Ensure your seed list is isolated from general mailing lists subject to engagement filters. Consider sending seed lists separately.
• Understanding discrepancies: Be aware that seed list results often differ from organic engagement data due to their passive nature.
• Automated processes: Account for any automated processes that might suppress non-engaged contacts, including seeds.

Key opinions

• Sender-side issues: Experts confirm that 'missing' seed list emails are technical problems originating from the sender, not reputation problems.
• Seed list isolation: A critical recommendation is to isolate seed lists in dedicated segments to prevent accidental exclusion by active filters.
• Engagement criteria: Since seeds do not engage, they will naturally fail engagement criteria and can be suppressed.
• Post-deployment suppression: The issue often arises from addresses being suppressed after the initial deployment stage.

Key considerations

• ESP platform checks: Experts advise a thorough review of the ESP's sending configurations and suppression lists. Delve into how deliverability seed list tools function.
• Segmentation impact: If segmentation relies on engagement, ensure seed addresses are explicitly whitelisted or excluded from these rules to prevent important emails going to spam.
• Time-based suppression: Investigate any automated time-based suppression mechanisms that could inadvertently remove seed addresses.
• Consult 250ok support: If issues persist, engaging directly with 250ok support can provide specific insights, as they often have visibility into the seed addresses' behavior. Insights from 250ok on improving email deliverability are valuable.

Key findings

• X-header requirement: Documentation often states that missing mail can occur if unique x-header values are not properly implemented.
• Reference addresses: Some systems highlight that only specific "reference addresses" within a seed list might be tested, not the entire list.
• Post-deployment suppression: Official guides mention that addresses can be suppressed after being sent if certain conditions are met by the ESP.
• Seed engagement: Documentation confirms that seed addresses are passive and do not engage, making them susceptible to engagement-based filtering.

Key considerations

• Consult provider's knowledge base: Refer to the specific knowledge base or support documentation of your seed list provider (e.g., 250ok) for detailed troubleshooting steps. For example, the 250ok knowledge base explains why your inbox test shows 100% missing mail.
• ESP suppression policies: Review your ESP's documentation regarding their suppression and filtering mechanisms. This includes using seed lists with multiple content versions.
• Mailer configuration: Ensure your email sending system is configured to deliver to all seed addresses consistently without unintended exclusions.
• Seed list function: Understand that seed list accounts typically do not engage, which is a key factor in deliverability testing. Learn how seed lists function for email deliverability.
• Accuracy considerations: Documentation often outlines the limitations and accuracy considerations of seed list testing compared to live engagement metrics.