Why am I experiencing a higher soft bounce rate for Gmail and iCloud email addresses?

Key findings

• Specific domain issue: The problem often targets specific domains like Gmail and iCloud, rather than a general increase across all email providers, suggesting unique filtering or rate limiting by these ISPs.
• Temporary recipient issues: Common soft bounce reasons include recipients' mailboxes being over quota or temporary rate limiting applied by the ISP to individual users.
• No widespread global issue: Industry observers and experts generally report not seeing a widespread, global issue affecting Gmail or iCloud soft bounces, implying the cause is often specific to the sender's practices.
• Sender reputation or volume: Factors such as sending to lapsed or unengaged subscribers, or a sudden increase in sending volume, can trigger stricter filtering and rate limiting by ISPs, leading to soft bounces. For more on this, read our article on why emails go to spam after high bounce rates.

Key considerations

• Analyze bounce reasons: The most crucial step is to examine the specific SMTP bounce codes and messages provided by your email service provider. These details often pinpoint the exact reason for the temporary failure. You can learn more about acceptable email bounce rates and bounce differences.
• Monitor sending patterns: Assess if there have been any changes in your sending volume, frequency, or the type of content being sent, especially to Gmail and iCloud addresses.
• Audience segmentation: Consider if you are sending to less engaged or older segments of your list that might be more prone to temporary issues or have high bounce rates. Our article on email bounce rates provides further insights into minimizing them.
• Patience and retry logic: Since soft bounces are temporary, your sending system should implement retry logic, allowing a delay before attempting to resend the email. Do not repeatedly try to send to persistently bouncing addresses.

Key opinions

• Diagnostic questions are key: Marketers frequently advise starting with fundamental questions like whether the content or subscriber list has changed to narrow down potential causes.
• Specific domain focus: When the issue is isolated to specific domains like Gmail or iCloud, it points towards unique filtering rules or capacity issues at those providers, rather than a universal problem with the sender.
• List hygiene importance: High bounce rates, even soft ones, can signal issues with list quality, such as inactive subscribers or potential spam traps. Keeping lists clean is crucial for deliverability. Our guide on fixing high email bounces delves deeper.
• Temporary nature of soft bounces: Marketers generally understand that soft bounces indicate temporary problems like a full mailbox or server issues, meaning a retry is often warranted.

Key considerations

• Examine campaign changes: Even if the campaign type is the same, new content might trigger filters. It is vital to review any recent content modifications.
• Segment analysis: Investigate if the higher soft bounce rates are coming from specific segments of your audience, such as less engaged or older subscribers, which could point to re-engagement campaign issues. We also have a guide on sudden spikes in Gmail bounce rates.
• Bounce logs: Prioritize reviewing detailed bounce logs from your email service provider. These logs contain the specific reasons for deferral or rejection, which are critical for diagnosis.
• Engagement metrics: Focus on metrics beyond open rates, particularly given changes like Mail Privacy Protection. High soft bounces can sometimes precede lower engagement or poor inbox placement.

Key opinions

• Bounce reasons are paramount: Experts stress that without examining the specific bounce errors, diagnosing the problem accurately is nearly impossible, particularly for domains like Gmail and GSuite.
• Rate limiting is common: Both Google and Apple ISPs frequently implement temporary rate limits on receiving mail, either for individual user accounts (e.g., over quota) or for the sender's volume, leading to soft bounces.
• Situational iCloud issues: Soft bounces from iCloud domains (like mac.com, me.com, apple.com) are often situation-dependent and can also be attributed to rate limiting of either the sender or the recipient.
• No widespread anomaly: Most experts have not observed a general uptick in soft bounces from these domains across the board, suggesting the issue is likely specific to the sender experiencing it. Our guide on troubleshooting high soft bounce rates provides a detailed approach.

Key considerations

• Sender reputation management: Maintaining a strong sender reputation is key to avoiding rate limiting and filtering. This involves consistent sending practices and monitoring engagement.
• Engagement-driven sending: ISPs increasingly prioritize engagement. Sending to unengaged subscribers can lead to soft bounces or even blocklisting (blacklisting) if ignored. Ensure your practices comply with boost email deliverability rates best practices.
• SMTP response interpretation: Understand the nuances of SMTP bounce codes. A '4xx' code typically indicates a temporary failure, allowing for retries, whereas a '5xx' code denotes a permanent one. You can refer to Google's official Receiving Rate documentation for more details.
• Monitor specific domains: If soft bounces are domain-specific, focus monitoring and troubleshooting efforts on those particular ISPs.

Key findings

• Recipient over quota: Google's documentation confirms that a 452 4.2.2 error means the recipient's email account has exceeded its storage quota.
• Receiving rate limits: Google also details 450-4.2.1 errors, indicating the user is receiving mail at a rate that temporarily prevents additional messages from being delivered.
• ICloud excessive volume: Apple's support documentation for iCloud indicates that messages can be deferred due to excessive volume (e.g., 421 4.7.1), a temporary state requiring later retry.
• Temporary nature: Across the board, documentation defines soft bounces as temporary failures due to issues like full mailboxes, server problems, or message size limits.

Key considerations

• Interpret SMTP codes: Familiarize yourself with standard SMTP response codes to understand the specific reasons for soft bounces, which guides appropriate retry strategies.
• Adhere to sending guidelines: Respect ISP-specific sending guidelines and volume limits. Exceeding these, even with good content, can lead to throttling. You can read up on why emails are suddenly rejected by Gmail.
• Retry mechanisms: Implement a robust retry system with exponential backoff for soft bounces, allowing sufficient time for temporary issues to resolve. For troubleshooting iCloud issues, see Apple's official support.
• Recipient education: If bounces are due to full mailboxes, encourage recipients to manage their storage. Google provides guidance for recipients when an account is over quota.