Summary
Recovering from a subscription bombing requires a comprehensive strategy encompassing immediate actions, prevention, and long-term reputation rebuilding. Key immediate steps involve stopping the email flood, suppressing affected subscribers, and investigating the attack's source. Prevention includes hardening signup processes with CAPTCHA or double opt-in and implementing rate limiting. Long-term, focus on warming up IP addresses, segmenting lists by engagement, monitoring reputation metrics (bounce/complaint rates), and implementing email authentication (SPF, DKIM, DMARC). Engaging with mailbox provider abuse desks, using email testing tools, and potentially using a new IP address or domain are also recommended.
Key findings
- Immediate Action: Stop and Suppress: Immediately halt email sends and suppress affected subscribers to prevent further damage to sender reputation.
- Identify and Secure the Source: Investigate the subscription bombing's source and implement measures like CAPTCHA or double opt-in to prevent recurrence.
- Reputation Rebuilding: Warm-up and Segment: Gradually warm up IP addresses by sending to engaged users and segment email lists based on engagement to rebuild reputation.
- Authentication and Monitoring: Implement SPF, DKIM, and DMARC and closely monitor sender reputation metrics (bounce/complaint rates) using tools like Google Postmaster Tools and Microsoft SNDS.
- Engage with Mailbox Providers: Contact abuse desks at major mailbox providers, providing details of the incident to begin reputation recovery.
Key considerations
- Time for Recovery: Reputation recovery takes time. Consistent effort and adherence to best practices are crucial.
- Proactive Monitoring: Continuously monitor your sending reputation and metrics to quickly identify and address issues.
- Compliance with Standards: Ensure compliance with industry standards and best practices for email authentication and list hygiene.
- Dedicated IP/Domain: Consider using a dedicated IP address or a new transactional domain to isolate deliverability issues.
- Testing and Optimization: Regularly test your emails for potential deliverability issues and optimize content to improve engagement and reduce spam complaints.
What email marketers say
10 marketer opinions
Improving transactional email deliverability after a subscription bombing requires a multifaceted approach. Immediate actions include pausing sends, suppressing affected email addresses, and identifying the attack's source to prevent recurrence (e.g., implementing CAPTCHA or double opt-in). Long-term strategies involve warming up IP addresses, segmenting email lists based on engagement, monitoring sender reputation metrics (bounce/complaint rates), and implementing email authentication (SPF, DKIM, DMARC). Contacting mailbox providers (like Apple) and using email testing tools (GlockApps, Email on Acid, Litmus) are also recommended. Creating a new transactional domain or dedicated IP may also help.
Key opinions
- Immediate Pause & Suppression: Immediately halt email sends and suppress the affected email addresses to prevent further damage to sender reputation and avoid triggering rate limits.
- Identify & Prevent Source: Determine the source of the subscription bombing and implement preventive measures such as CAPTCHA, double opt-in, or signup form fortification to avoid future incidents.
- Warm-up & Segmentation: Gradually warm up IP addresses by sending to highly engaged users first and segment email lists based on engagement to rebuild sender reputation.
- Monitor Reputation & Metrics: Closely monitor sender reputation metrics like bounce rates, complaint rates, and blocklist status to identify and address deliverability issues.
- Implement Authentication: Implement SPF, DKIM, and DMARC email authentication protocols to verify sender identity and improve trust with ISPs and mailbox providers.
Key considerations
- Time for Reputation Recovery: Understand that improving deliverability after a subscription bombing is a gradual process that requires time and consistent effort to rebuild sender reputation.
- Contact Mailbox Providers: Engage with abuse desks at major mailbox providers (e.g., Apple, Google, Microsoft) and provide them with detailed information about the incident and steps taken to resolve it.
- Utilize Email Testing Tools: Use email testing tools to identify potential deliverability issues such as broken links, spam trigger words, or authentication problems.
- Consider Dedicated IP/Domain: Consider creating a dedicated IP address or a new transactional domain to isolate deliverability issues and prevent them from affecting marketing emails.
- Audit Subscription Process: Regularly audit your subscription processes and email list hygiene to remove inactive or invalid addresses and maintain a healthy sending reputation.
Marketer view
Email marketer from Mailgun recommends implementing a double opt-in process to confirm subscriptions, closely monitoring sender reputation metrics (like bounce rates and complaint rates), segmenting email lists to target engaged users, and warming up IP addresses to establish a positive sending history. Furthermore they say to authenticate email with SPF, DKIM and DMARC.
11 Oct 2024 - Mailgun
Marketer view
Email marketer from StackOverflow user EmailDev suggests implementing a suppression list to immediately remove all known problematic email addresses. They highlight segmenting email lists based on user engagement and sending to most engaged users first to rebuild sender reputation. They also mention that carefully monitor bounce rates and complaints, adjusting sending volume as needed.
15 Aug 2021 - StackOverflow
What the experts say
2 expert opinions
Recovering from a subscription bombing requires immediate action and careful investigation. Experts recommend stopping the email flow to prevent rate limits and further reputation damage. Engaging with mailbox provider abuse desks and detailing the incident is vital for reputation recovery. Identifying and suppressing affected subscribers is crucial, followed by a thorough investigation of the attack's origin to secure signup processes and prevent future abuse.
Key opinions
- Stop the Email Flood: Immediately halt sending to avoid triggering rate limits and further harming sender reputation.
- Engage with Abuse Desks: Contact abuse desks at major mailbox providers, providing details of the incident to begin reputation recovery efforts.
- Identify and Suppress: Identify affected subscribers and immediately suppress them to prevent further email delivery to those addresses.
- Investigate the Source: Thoroughly investigate the attack's source to understand how the subscription bombing occurred.
- Harden Signup Processes: Review and harden signup processes to prevent future abuse.
Key considerations
- Reputation Recovery: Engaging with abuse desks is important for your sending domain's reputation
- Long-Term Prevention: Address signup processes to make sure it does not happen again
- Throttling: Make sure your sending systems have the ability to throttle sends to prevent further damaging sender reputation
Expert view
Expert from Spam Resource suggests immediately throttling sending to avoid triggering rate limits and further damaging sender reputation. It then highlights the importance of identifying affected subscribers, suppressing them immediately, and then to investigate the source of the attack.
2 Oct 2024 - Spam Resource
Expert view
Expert from Word to the Wise, Laura Atkins, advises that immediately stopping the flood of emails is key. She also states that it's important to engage with abuse desks at major mailbox providers and provide them with the details of the incident to start reputation recovery. In addition, she highlights the importance of reviewing your signup processes and hardening them against abuse.
30 May 2022 - Word to the Wise
What the documentation says
3 technical articles
Improving transactional email deliverability after a subscription bombing requires diligent monitoring and adherence to established guidelines. Google Postmaster Tools emphasizes domain/IP reputation monitoring, low spam complaint rates (below 0.10%), and proper authentication. Microsoft suggests using JMRP to identify and remove users marking emails as junk and using SNDS to monitor IP reputation. RFC documentation underscores the importance of implementing SPF, DKIM, and DMARC for sender authentication to combat spoofing and enhance trust.
Key findings
- Monitor Reputation: Utilize Google Postmaster Tools and Microsoft SNDS to monitor domain and IP reputation for identifying deliverability issues.
- Reduce Spam Complaints: Maintain a low spam complaint rate (below 0.10%) to improve inbox placement, especially in Gmail.
- Authenticate Emails: Implement SPF, DKIM, and DMARC email authentication protocols to verify sender identity and prevent spoofing.
- List Hygiene: Use Microsoft JMRP to identify and remove users marking emails as junk, ensuring proper list hygiene.
- Adhere to Guidelines: Adhere to sender guidelines provided by Google and other mailbox providers to improve deliverability.
Key considerations
- Proactive Monitoring: Regularly monitor your sending reputation and metrics to quickly identify and address any issues that may arise.
- Compliance with Standards: Ensure your email infrastructure complies with industry standards and best practices for email authentication.
- Continuous Improvement: Continuously improve your sending practices based on feedback and data from monitoring tools and mailbox providers.
Technical article
Documentation from Microsoft suggests using the Junk Email Reporting Program (JMRP) to identify users marking your emails as junk. Microsoft suggests removing these users from your sending lists and ensuring proper list hygiene. Furthermore they suggest joining their Smart Network Data Services (SNDS) program to monitor your IP reputation and identify potential issues affecting deliverability to Outlook.com users.
6 Apr 2025 - Microsoft
Technical article
Documentation from RFC explains the importance of implementing proper email authentication standards (SPF, DKIM, DMARC) as described in RFC specifications. RFC Documentation indicates these protocols allow receiving mail servers to verify the authenticity of the sender and combat spoofing, which can significantly improve email deliverability and trust with ISPs.
15 May 2024 - RFC-Editor
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