Why am I seeing an increase in bounce code 60 from SES?

Key findings

• Code 60 indication: Amazon SES bounce code 60 primarily signifies an automatic reply, such as an out-of-office message or vacation responder, rather than a delivery failure due to an invalid address or technical issue.
• Not a hard bounce: Unlike hard bounces, which indicate permanent delivery failures and should lead to immediate suppression, bounce code 60 does not necessarily imply that the email address is invalid.
• Volume fluctuations: Increases in this bounce code can be seasonal (e.g., during holiday periods when many recipients set auto-replies) or campaign-specific (e.g., sending to corporate lists with widespread out-of-office messages).
• SES classification: Amazon SES tracks various bounce types to help senders manage their lists and maintain good sending reputation. Understanding these specific codes is crucial for accurate list hygiene and deliverability analysis. You can learn more about how Amazon SES handles high bounce rates.
• Impact on metrics: While not directly harmful to sender reputation in the same way as hard bounces, a high volume of auto-replies can skew bounce rate metrics and make it harder to identify genuine deliverability issues. It's important to differentiate these from other bounce types.

Key considerations

• Monitoring: Continuously monitor your bounce rates and specifically the types of bounces you receive. Identifying a specific code like 60 allows for targeted analysis and response.
• Segmentation: If you observe a significant increase in bounce code 60, consider segmenting your bounce data to understand which campaigns or recipient groups are generating these responses. This can help you refine your sending strategy.
• List hygiene: While auto-replies don't typically require immediate suppression, a high volume might indicate an unengaged list. Regularly cleaning your list by removing inactive or non-responsive addresses can improve overall engagement and reduce unwanted bounces. Discover what causes sudden bounce spikes.
• Distinguish from hard bounces: Ensure your system is correctly classifying and handling different bounce types. True hard bounces (like 'mailbox not found' errors) should result in immediate suppression to protect your sender reputation. Learn about why Gmail hard bounces occur.
• Reputation management: Focus on maintaining low rates of harmful bounces and complaints, as these are the primary factors affecting your sender reputation and inbox placement. A high rate of bounce code 60 alone is unlikely to damage reputation, but it can mask underlying list quality issues.

Key opinions

• Increased volume noted: Many marketers are observing a recent increase in SES bounce code 60, particularly over the last few weeks, indicating a shift in bounce patterns or a heightened awareness of this specific code.
• Auto-reply association: There is a strong consensus among marketers that bounce code 60 from SES typically represents auto-replies, such as out-of-office messages, rather than permanent delivery failures.
• Data interpretation challenges: Marketers find it challenging to interpret these codes correctly, as they can sometimes be ambiguous or require deeper investigation into the full bounce message to confirm their nature. For example, Amazon SES uses a suppression list for some bounces.
• Impact on deliverability: While not critical, a surge in these bounces prompts marketers to question whether it's indicative of broader deliverability issues or simply a reporting anomaly.
• System specific nature: Some marketers suspect that code 60 might be an internal SES-specific code, suggesting that its meaning could be unique to the platform and not a universal SMTP bounce code.

Key considerations

• Review bounce logs: Marketers should regularly review their Amazon SES bounce logs to identify specific bounce types and assess if there's an actual increase in problematic bounces versus informational ones like auto-replies.
• Understand bounce categories: It is crucial to differentiate between soft bounces (temporary issues), hard bounces (permanent failures), and informational bounces (like auto-replies) to apply appropriate list management strategies. This helps in understanding why soft bounce rates increase.
• List engagement: While auto-replies do not directly harm sender reputation, a consistent high volume could signal a need to re-engage or clean segments of your list that are less active.
• Tool integration: Ensure your marketing automation or email service provider integrates effectively with SES bounce notifications to categorize and act on bounces appropriately, preserving your email domain reputation.

Key opinions

• Internal SES code: Experts often view bounce code 60 as an internal classification by Amazon SES for auto-reply type messages, which may not correspond to standard SMTP bounce codes but is specifically reported by the platform.
• No aggregate trend: Some experts indicate they haven't observed a widespread, aggregate increase in bounce code 60 across various clients or systems, suggesting that an observed increase might be specific to an individual sender's campaigns or list.
• Informational nature: The consensus is that bounce code 60 is generally informational, reflecting an 'out of office' or similar auto-response, and typically doesn't signal a fundamental deliverability problem.
• Risk assessment: While not directly harmful, experts stress the importance of distinguishing these informational bounces from hard bounces, which necessitate immediate suppression to protect sender reputation and avoid blacklisting (or blocklisting) issues. Discover what happens when your domain is blocklisted.
• Data granularity: To fully understand any bounce increase, experts recommend looking at the full bounce message and not just the code. This provides context and helps identify the root cause, whether it's a transient issue or something more serious affecting email deliverability.

Key considerations

• Contextual analysis: Analyze bounce code 60 in the context of your overall sending patterns and recipient engagement. A sudden spike might relate to specific campaign timings or target demographics.
• List hygiene practices: Maintain robust list hygiene practices that differentiate between temporary auto-replies and permanent invalid addresses. While you don't necessarily remove recipients for code 60, prolonged non-engagement might warrant list cleaning.
• Monitor deliverability metrics: Pay close attention to your Amazon SES compliance rates and overall bounce percentages. If these metrics significantly increase, it's a red flag requiring immediate investigation into the underlying causes, as accounts exceeding certain bounce thresholds can be suspended.
• Authentication checks: Ensure your email authentication records (SPF, DKIM, DMARC) are correctly configured. While unrelated to auto-replies, proper authentication is fundamental to good deliverability and can prevent other types of bounces or blocklisting issues. Learn about DMARC, SPF, and DKIM.

Key findings

• Bounce types: AWS documentation categorizes bounces broadly into hard bounces (permanent failures) and soft bounces (temporary failures). While 'auto-reply' is often listed as a specific type of bounce, it's typically treated as informational or a soft bounce.
• Compliance thresholds: Amazon SES strongly recommends maintaining bounce rates below 2%. Accounts exceeding 5% may be placed under review, and those consistently above 10% risk suspension. These thresholds primarily refer to hard bounces and complaints, not typically auto-replies. Learn more about this from Medium on handling SES bounces.
• Suppression list: Amazon SES maintains a suppression list to prevent sending emails to addresses that have previously resulted in hard bounces or complaints. Auto-reply bounces (like code 60) do not typically lead to an address being added to this list.
• Bounce notifications: SES provides detailed bounce notifications via Amazon SNS, allowing senders to programmatically process bounces and manage their mailing lists. These notifications include specific bounce types and codes.
• SMTP vs. SES codes: Some SES-specific bounce codes (like 60) may be internal classifications by AWS rather than direct SMTP reply codes (e.g., 550, 421). This means their interpretation might be unique to the SES platform.

Key considerations

• Automated bounce processing: Implement automated systems to parse SES bounce notifications and distinguish between hard, soft, and informational bounces. This ensures only permanently undeliverable addresses are removed.
• Reputation best practices: Follow AWS best practices for maintaining a healthy sender reputation, which includes sending to engaged audiences, using proper authentication (SPF, DKIM, DMARC), and promptly removing addresses that generate hard bounces or complaints. This helps to prevent SES email delivery issues.
• Monitoring dashboard: Regularly check the Amazon SES console's reputation dashboard for insights into your bounce and complaint rates, which are key indicators of your account's health.
• List validation: Although auto-replies don't mean an address is invalid, frequent soft bounces of any kind could signal a need for more stringent list validation practices to ensure you are reaching active inboxes.