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10-Email Optimizing Bounce Handling For Marketers

by Anil Jalela | Oct 10, 2024 | Linux

In email marketing, maintaining a low bounce rate is crucial for deliverability, sender reputation, and the overall success of email campaigns. Bounces occur when an email fails to reach the intended recipient, leading to lost opportunities for engagement.

There are two types of bounces: hard bounces (permanent failures) and soft bounces (temporary issues). If these bounces aren’t handled properly, they can significantly affect email deliverability, damage IP and domain reputation, and reduce the effectiveness of marketing efforts.

This case study explores a scenario where an email marketing team at an e-commerce company struggled with high bounce rates, particularly after launching a series of new promotional campaigns. The goal was to improve bounce handling practices, reduce bounce rates, and enhance overall deliverability.

Objective:

To reduce bounce rates and improve email deliverability by optimizing the management of bounced emails, ensuring list hygiene, and enhancing email campaign strategies.

Initial Challenges:

The marketing team faced several issues that contributed to high bounce rates:

Poor List Hygiene: The team had not cleaned their email list regularly, resulting in a significant number of invalid email addresses.
Insufficient Bounce Management: Hard bounces were not removed promptly, and soft bounces were being retried too frequently, leading to repeated delivery failures.
Lack of Authentication: The emails lacked proper authentication protocols, such as SPF and DKIM, causing many ISPs to reject them or flag them as suspicious.
Content Triggers: Certain campaigns had high bounce rates due to content flagged by spam filters, such as overly promotional language and excessive use of images.

Step-by-Step Approach to Optimize Bounce Handling:

Error Identification Process:

• Bounce Codes: Analyze bounce codes provided by ISPs. These codes indicate specific issues, such as invalid addresses (hard bounce), temporary server issues (soft bounce), or content-related rejections.
• Authentication Failures: Monitor failures related to SPF, DKIM, and DMARC authentication. Failures in these protocols may result in delivery rejections.
• Feedback Loops (FBL): Set up FBLs with major ISPs to receive spam complaint data. High complaint rates are a warning sign of errors in targeting or list quality.
• ISP-Specific Issues: Monitor inbox placement reports from ESPs and tools like Return Path to check if any ISPs are particularly resistant to your emails.
• Domain Reputation: Use reputation monitoring tools (e.g., Google Postmaster, SenderScore) to identify domain or IP reputation issues.
• Spam Filters: Check if your emails are being flagged by spam filters due to content triggers, poor formatting, or overly promotional language.

1. Email List Hygiene

Problem: The marketing team was sending emails to an outdated list containing inactive, invalid, and misspelled addresses.
Solution:
=> List Cleaning: The team conducted an in-depth list cleaning process using email verification tools like ZeroBounce and NeverBounce to remove invalid and undeliverable addresses. This helped reduce hard bounces immediately.

=> Double Opt-In: They implemented a double opt-in process for new subscribers to ensure email validity from the start, reducing the chances of fake or incorrect email addresses entering the list.

Outcome: Hard bounce rates dropped by 50% after the first round of list cleaning, leading to an immediate improvement in sender reputation.

2. Hard and Soft Bounce Management

Problem: The team was retrying failed email deliveries excessively, especially for soft bounces, which annoyed some ISPs and further damaged sender’s reputation.

Solution:
=> Hard Bounce Removal: They set up automated processes to remove hard bounces immediately after the first occurrence, ensuring they weren’t included in future sends.
=> Soft Bounce Handling: Soft bounces were monitored more closely, with a threshold set to retry emails only twice. After three soft bounces over consecutive campaigns, the email addresses were moved to a suppression list.

    Threshold: Depending on your email sending frequency and strategy, the exact number may vary, but 3 to 5 soft bounces is a common rule of thumb.
ISP Guidelines: Some ISPs may have their own soft bounce limits, and monitoring the responses can help you fine-tune your threshold.

Best Practices:

• Use a Bounce Management System: Centralized bounce handling can be done using email service provider (ESP) tools that automatically capture, analyze, and report bounce codes.
• Real-Time Bounce Tracking: Implement real-time tracking for bounces so that your system can immediately process and react to bounce types (soft vs. hard).
• Create Suppression Lists: Set up centralized suppression lists for hard bounces, invalid addresses, and users who have marked emails as spam. This ensures that bounces are managed across all campaigns and tools.
• Consolidate Bounce Logs: Integrate your bounce logs from multiple sending platforms to avoid duplication and ensure every email address is handled properly across campaigns.
• Monitor Feedback Loops (FBL): Centralize spam complaint data from ISPs to ensure prompt removal of flagged addresses.

Outcome: The team saw a significant reduction in the volume of emails sent to non-deliverable addresses, and overall soft bounce rates fell by 30%.

3. Improving Authentication Protocols

Problem: A lack of proper email authentication led ISPs to reject or filter out legitimate emails.
Solution:
SPF and DKIM: The team implemented SPF and DKIM authentication to prove that emails were being sent by authorized servers and hadn’t been altered during transit.
DMARC Policies: They also configured DMARC policies to further enhance security and provide reporting on email authentication issues.

Outcome: With SPF, DKIM, and DMARC properly set up, bounce rates related to authentication failures were minimized, and deliverability improved by 15%.
4. Content Optimization

Problem: Some campaigns triggered spam filters due to poor content choices, such as using all caps in subject lines, too many promotional keywords, and unoptimized images.
Solution:
Subject Line Testing: The team ran A/B tests to find more balanced and effective subject lines that didn’t trigger spam filters.
HTML Optimization: They optimized the HTML structure of their emails, reducing image-heavy content and ensuring the code was clean and responsive.
Avoiding Spammy Language: The team reduced the use of overly promotional words and phrases like “FREE,” “BUY NOW,” and “LIMITED TIME,” which often triggered spam filters.

Outcome: After optimizing content, spam complaints decreased, and soft bounces related to content issues dropped by 20%.
5. Throttling and Sending Practices

Problem: Sending too many emails at once was overwhelming some ISPs, resulting in delivery blocks.
Solution:
Throttling: The team introduced email throttling to gradually send emails, preventing large volumes from being sent in a short period.
Segmentation: By segmenting their audience, they prioritized sending emails to the most engaged users first, which improved their overall sender reputation.

Segmentation Rating System & Strategies:

• Engagement Metrics: Use engagement rates like open rates, click-through rates, and conversion rates to assign scores to each email address.
  • High-engagement users (e.g., those who open or click frequently) should be rated highly.
  • Low-engagement or inactive users can be assigned a lower score or flagged for a re-engagement campaign.
• Bounce and Complaint History: If an email address has a history of bounces or spam complaints, it should be given a low rating or suppressed altogether.
• Segmentation: Create separate ratings for each list segment based on factors such as the age of the list, source (organic vs. purchased), and engagement history.
• List Age: Older lists that haven’t been cleaned or engaged with in a while may warrant a lower rating.
• Assign Ratings:
  • A-Rating: Highly engaged and active users.
  • B-Rating: Moderately engaged, possible re-engagement candidates.
  • C-Rating: Inactive or unengaged users, likely to be pruned or re-engaged.
    

Segmentation Strategies:

• Engagement-Based Segmentation:
  • Active Subscribers: Create a segment of users who frequently open or click emails. These are your most valuable subscribers and should be targeted with more frequent or personalized content.
  • Inactive Subscribers: Segment users who haven’t opened or clicked an email in a defined time frame (e.g., 6 months). You can send them a re-engagement campaign or move them to a suppression list if they remain inactive.
• Demographic-Based Segmentation:
  • Use demographic data like location, gender, or age to send targeted offers. For example, if you’re marketing a retail brand, you can send location-specific promotions.
• Behavioral Segmentation:
  • Purchase History: Segment users based on their purchase behavior. Send follow-up emails, upsell offers, or loyalty rewards based on past purchases.
  • Browsing Activity: For e-commerce businesses, segment users based on their browsing behavior on your website (e.g., sending product recommendations based on recently viewed items).
• Content Preferences: Based on user preferences (from past interactions or surveys), send segmented content that matches their interests, whether it’s product-focused, informative, or educational.
• Re-Engagement Segmentation: Create segments specifically for re-engagement campaigns targeting users who have not interacted in a certain period.

 By using segmentation, you’ll improve the relevance of your emails, reduce bounce rates, and enhance engagement. Well-segmented campaigns also help ISPs recognize your emails as valuable and legitimate, boosting your deliverability.

Outcome: Throttling reduced ISP-related blocks, and segmentation ensured better engagement, further improving sender reputation and reducing bounces.

Results:
By implementing these bounce-handling optimizations, the email marketing team was able to achieve the following:
Reduced Hard Bounce Rates by 50%: Thanks to improved list hygiene and prompt hard bounce removal.
Lowered Soft Bounce Rates by 30%: Through better handling of soft bounces and limiting retries.
Increased Deliverability by 20%: Authentication improvements and content optimization helped emails bypass spam filters and reach the inbox.
Boosted Sender Reputation: Throttling, proper segmentation, and feedback loop monitoring led to fewer complaints and higher engagement rates.

Conclusion:

This case study demonstrates the importance of effective bounce handling and how it can significantly impact email marketing performance. By focusing on list hygiene, proper bounce management, authentication, and content optimization, the marketing team not only reduced bounces but also improved deliverability and engagement. Email marketers should continually monitor their bounce rates, sender reputation, and email content to maintain a healthy email marketing program.

Key Takeaways:

List hygiene is critical to reducing bounces and maintaining a clean email list.
Hard and soft bounce handling should be automated and managed carefully to avoid damage to sender’s reputation.
Authentication protocols (SPF, DKIM, DMARC) are essential for gaining ISP trust and improving email deliverability.
Content optimization helps prevent spam filtering and keeps bounce rates low.
Throttling and segmentation can reduce delivery blocks and improve engagement.

By following these best practices, email marketers can ensure a more effective, high-deliverability email strategy.