Summary
Deliverability issues arising after the winning email from an A/B test is sent, despite initial inbox placement, are multifaceted. Key contributing factors include: volume inconsistencies (sudden spikes triggering spam filters), changes in content (introducing spam triggers), degradation of list quality (presence of spam traps/inactive addresses), inaccurate test environments (spam filters adapting), inconsistent email authentication (SPF, DKIM, DMARC), and non-compliance with email standards. Further considerations involve sender reputation (impacted by sending frequency, engagement, complaints), the timing of the send, and list segmentation. Using different IP addresses for the test and the final send, poorly managed seed lists, and unmonitored feedback loops also exacerbate these problems.
Key findings
- Volume: Sudden volume spikes after the test send trigger spam filters; dedicated IPs require consistent volume.
- Content: Changes in content in the winning email may contain spam triggers missed in the test.
- List Quality: Degradation of list quality, including spam traps or inactive accounts, degrades deliverability.
- Test Environment: Test environment differs from live conditions; spam filters learn and adapt over time.
- Authentication: Inconsistent email authentication (SPF, DKIM, DMARC) causes deliverability failures.
- Sender Reputation: Sender reputation is affected by sending frequency, engagement rates, and complaint rates.
- Timing: Sending at different times of day affects user engagement and deliverability.
- Segmentation: Inadequate segmentation impacts the winner’s performance in segments not included in the test.
- IP Address: Using a different IP address for the full send than the test affects deliverability.
Key considerations
- IP Warming: Gradually warm up IPs, maintaining consistent sending volumes; consider dedicated IP requirements.
- Content Review: Thoroughly review winning email content for spam triggers; perform content analysis.
- List Cleaning: Regularly clean lists to remove inactive addresses and spam traps; segment lists effectively.
- Testing Tools: Use seed list testing services for real-world spam filter assessment; ensure test environment is representative.
- Authentication Setup: Ensure correct email authentication settings are in place (SPF, DKIM, DMARC) for both test and live sends.
- Monitor Reputation: Monitor sender reputation using Google Postmaster Tools and Microsoft SNDS.
- Sending Frequency: Maintain a consistent sending cadence.
- Feedback Loops: Monitor feedback loops (complaints) to address issues.
- Schedule Alignment: Ensure that the scheduling is aligned with user engagement.
- Seed List Health: Seed list is in an active state.
What email marketers say
13 marketer opinions
The deliverability issues after sending the 'winner' of an email A/B test, despite the initial test inboxing successfully, stem from various factors. Volume inconsistencies, changes in content triggering spam filters, list quality degradation, inaccurate test environments, and inconsistent email authentication all contribute. Sender reputation, influenced by sending frequency, engagement rates, and complaint rates, plays a critical role. The timing of the send, list segmentation, IP addresses, and feedback loops can also significantly impact deliverability.
Key opinions
- Volume: Significant volume spikes after the test send can trigger spam filters. Inconsistent IP volume can cause reputation issues.
- Content: Changes in content from the test to the winner can trigger spam filters.
- List Quality: List quality degradation (spam traps, inactive addresses) between test and full send negatively impacts deliverability.
- Test Environment: The test environment might not accurately represent live conditions; spam filters adapt and learn.
- Sender Reputation: Sender reputation (influenced by sending frequency, engagement, and complaints) is crucial for deliverability.
- Time of day: Sending the 'winner' at a significantly different time of day can affect deliverability.
Key considerations
- IP Warming: Gradually warm up IP addresses, especially for new IPs, and maintain consistent sending volumes.
- Content Review: Thoroughly review the content of the winning email for potential spam triggers.
- List Cleaning: Regularly clean email lists to remove inactive addresses and spam traps.
- Testing Tools: Use seed list testing services to test against real-world spam filters.
- Authentication: Ensure correct configuration of email authentication settings (SPF, DKIM, DMARC) for all sends.
- Segmentation: Ensure all segments are properly represented during testing.
- Feedback Loops: Monitor feedback loops for complaints to gauge reputation and address issues.
- Send Time: Do you understand how sending at different times of the day affect user engagement.
Marketer view
Email marketer from Email Geeks suggests that volume could be the issue, regardless of the A/B test split, as the total volume might be significantly higher than usual.
27 Jan 2025 - Email Geeks
Marketer view
Email marketer from SendGrid shares that changes in content from the test to the winner can affect deliverability. If the winning email has elements that trigger spam filters (certain keywords, excessive links, etc.), it can cause issues even if the initial test passed. They suggest reviewing the content of the winning email for potential spam triggers.
14 Sep 2024 - SendGrid
What the experts say
5 expert opinions
The deliverability issues following the deployment of a winning A/B test email can be attributed to several factors. Inconsistent timing or day of the week between the test and full send can influence deliverability. Inadequate list segmentation, where the winning version performs poorly with segments not included in the test, and a poorly managed seed list can also contribute. Changes in sending frequency and the use of a different IP address for the full send compared to the test can negatively impact sender reputation and, therefore, deliverability.
Key opinions
- Timing and Day: Inconsistent timing or day of the week between the A/B test and the winner send can affect deliverability.
- List Segmentation: Inadequate list segmentation can lead to poor performance of the winning version with untested segments.
- Seed List Management: A poorly managed or inactive seed list can misrepresent true deliverability.
- Sending Frequency: Changes in sending frequency can impact sender reputation and deliverability.
- IP Address Consistency: Using a different IP address for the full send compared to the test can negatively impact deliverability.
Key considerations
- Consistent Scheduling: Maintain consistent timing and day of the week between A/B tests and the deployment of the winning version.
- Comprehensive Segmentation: Ensure all relevant list segments are represented during the A/B testing phase.
- Active Seed List: Regularly check and maintain an active and representative seed list.
- Stable Sending Frequency: Avoid abrupt changes in sending frequency, as they can affect sender reputation.
- IP Address Alignment: Ensure the same IP address is used for both A/B testing and the full deployment of the winning email.
Expert view
Expert from Word to the Wise shares that potential cause may be due to sending the full 'winner' send using a different IP address. When testing ensure the IP you are using is the same as future sends.
26 Jul 2023 - Word to the Wise
Expert view
Expert from Spam Resource explains that inadequate list segmentation might be the cause. The winning version might perform poorly with segments that weren't included in the initial A/B test, leading to lower engagement and deliverability issues. Ensure all segments are properly represented during testing.
17 Aug 2024 - Spam Resource
What the documentation says
4 technical articles
Deliverability issues occurring after an email A/B test's winner is sent are often linked to technical factors and sender reputation. Documentation from Google and Microsoft highlights that sudden volume increases and fluctuations in engagement negatively affect sender reputation, triggering spam filters. Inconsistent email authentication (SPF, DKIM, DMARC), as pointed out by RFC-Editor, and failure to adhere to up-to-date email standards, per IETF, also contribute to deliverability problems.
Key findings
- Volume Spikes: Sudden increases in email volume after the A/B test can trigger spam filters.
- Sender Reputation Impact: Fluctuations in sending volume and engagement negatively impact sender reputation.
- Authentication Inconsistencies: Inconsistent email authentication (SPF, DKIM, DMARC) leads to deliverability issues.
- Standards Non-Compliance: Failure to adhere to up-to-date email standards can result in emails being flagged as spam.
Key considerations
- Ramping Up Sending: Gradually ramp up sending practices, especially for new IPs or domains.
- Reputation Monitoring: Monitor sender reputation using tools like Google Postmaster Tools and Microsoft SNDS.
- Authentication Setup: Ensure email authentication settings (SPF, DKIM, DMARC) are correctly configured.
- Standards Compliance: Adhere to up-to-date email standards to ensure emails are properly formed.
Technical article
Documentation from IETF explains that adherance to up to date email standards help prevent being flagged as spam. Ensuring your emails are properly formed with all necessary headers, and conforming to internet standards around DNS, SPF etc means your emails will not be flagged.
12 Feb 2024 - IETF
Technical article
Documentation from RFC-Editor explains that inconsistent email authentication (SPF, DKIM, DMARC) can cause deliverability issues. Ensure that your email authentication settings are correctly configured for both test and full sends. Incorrect setup can lead to failed authentication and spam filtering.
11 Jan 2025 - RFC-Editor
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