Why is there a sharp increase in soft bounces from iCloud email addresses?
Matthew Whittaker
Co-founder & CTO, Suped
Published 24 Jul 2025
Updated 16 Aug 2025
6 min read
Experiencing a sudden surge in soft bounces from iCloud email addresses can be incredibly frustrating. It often feels like you're sending emails into a void, especially when your engagement metrics are otherwise stable. This issue can significantly impact your campaign performance and overall email deliverability.
Unlike hard bounces, which indicate a permanent delivery failure, soft bounces are temporary. The email server temporarily rejected the message, often with a specific reason that isn't always immediately clear. While the issue might resolve itself, a sharp increase suggests a more systemic problem that needs your attention.
Why iCloud stands out
Understanding soft bounces and their causes
What is a soft bounce?
A soft bounce occurs when an email temporarily fails to reach the recipient's inbox. This differs from a hard bounce, which signifies a permanent failure, such as an invalid email address. Soft bounces are often retried by the sending server for a period, typically 24-72 hours, before being marked as a final bounce.
Common reasons for soft bounces include the recipient's mailbox being full, the email server being temporarily unavailable, or the message size exceeding the recipient's server limits. Sometimes, the bounce can also be due to content-related issues or the sender's IP being temporarily blocked or greylisted.
While soft bounces are temporary, they can accumulate and negatively affect your sender reputation if not addressed promptly. A high soft bounce rate signals to Internet Service Providers (ISPs) like Apple that your sending practices might be problematic, leading to stricter filtering or even blocklisting (or blacklisting) of your emails.
When you see a significant uptick specifically from iCloud addresses, it points to a pattern that's likely tied to how Apple handles incoming mail. Their systems are highly sophisticated and prioritize user experience and privacy, which often means aggressive filtering against anything that might resemble spam or unwanted mail.
Sender reputation and iCloud's filtering
Apple's Mail Privacy Protection (MPP), introduced with iOS 15, has changed how email marketing metrics are tracked, but its direct impact on soft bounces is primarily related to engagement signals. While MPP obfuscates open rates, Apple's algorithms still monitor various engagement signals to determine sender reputation. A lack of positive engagement, or an increase in negative engagement (like users moving messages to junk), can trigger stricter filtering.
Another factor is Apple's Private Relay feature, which allows users to generate unique, anonymized email addresses. While these are designed to forward to the user's actual inbox, issues with these relay addresses or a high volume of emails sent to unengaged Private Relay users can contribute to soft bounces. For more details, consider reading about why Apple Private Relay accounts soft bounce.
Apple's anti-spam measures are also highly sensitive to sudden spikes in volume or changes in sending patterns. If you've recently increased your sending frequency, sent to an older segment, or modified your email content significantly, this could be perceived as suspicious activity, leading to temporary blocks or throttling, which manifest as soft bounces.
General soft bounce causes
Full mailbox: The recipient's inbox has reached its storage capacity.
Server unavailable: The recipient's email server is temporarily down or offline.
Message too large: The email exceeds the size limit set by the recipient's server.
Temporary block: The sending IP or domain is temporarily blacklisted (or blocklisted).
iCloud-specific soft bounce issues
Engagement signals: Low engagement rates or high spam complaints can trigger stricter filtering.
Private relay: Issues with Private Relay addresses or sending to unengaged relay users.
Volume spikes: Sudden increases in sending volume or frequency can be flagged as suspicious.
Content issues: Content that triggers spam filters, even subtly, can lead to soft bounces.
Practical steps to diagnose and resolve
Your sender reputation is paramount when dealing with major ISPs like Apple. A low reputation score, whether due to high bounce rates, spam complaints, or low engagement, can cause your emails to be throttled or outright rejected. iCloud, like Google and other major providers, uses sophisticated algorithms to protect its users from unwanted mail.
If you're seeing a sharp increase in soft bounces, it often means that iCloud's systems have started to view your sending domain or IP address with suspicion. This can happen if your email list contains a high percentage of inactive or disengaged users, leading to low open and click rates and potentially more spam complaints.
Maintaining a clean and engaged list is crucial for a healthy sender reputation. Regularly scrubbing your list to remove unengaged subscribers and invalid addresses helps ensure that your emails reach active inboxes, improving your overall deliverability. This also reduces the likelihood of hitting spam traps, which can quickly damage your reputation and lead to blocklisting (or blacklisting).
Continuous monitoring and list hygiene
The first step in troubleshooting soft bounces, especially when an Email Service Provider (ESP) only shows a generic 'soft bounce' message, is to try and get the underlying bounce codes. Contacting your ESP's support team is often the best way to obtain these detailed messages. They can provide specific error codes that indicate the exact reason for the bounce, which is vital for effective diagnosis.
Once you have the bounce messages, you can identify patterns. Are they all related to full mailboxes? Or do they indicate content-related issues or temporary blocks? This information will guide your remediation efforts. For common iCloud, me.com, and mac.com bounce troubleshooting, there's a dedicated guide available.
Beyond bounce codes, review your sending practices. Analyze your sending frequency and volume to iCloud addresses. Ensure your email authentication (SPF, DKIM, and DMARC) is correctly configured and aligned. A common issue is SPF DNS timeout with Microsoft, for example. Even though we're talking about iCloud, similar authentication principles apply. These records help mail servers verify that your emails are legitimate, which is critical for deliverability.
Finally, monitor your iCloud Postmaster information. This resource, while less comprehensive than Google Postmaster Tools, can offer insights into any specific delivery issues or advisories from Apple regarding your sending domain.
Views from the trenches
To prevent future spikes in soft bounces, continuous monitoring of your email deliverability metrics is essential. Pay close attention to your bounce rates, complaint rates, and engagement levels for all major ISPs, particularly iCloud. Early detection of rising bounce rates allows for quicker intervention before the problem escalates.
Implementing a robust list hygiene strategy is also critical. Regularly remove inactive subscribers who haven't engaged with your emails in a significant period. This reduces the number of emails sent to potentially abandoned or full mailboxes, improving your overall sender reputation and reducing the likelihood of soft bounces. For more on this, consider our guide on why your emails fail.
Finally, ensure your email content is relevant, engaging, and avoids spam trigger words. Personalization and segmentation can help boost engagement, signaling positive behavior to ISPs and improving inbox placement. A proactive approach to email deliverability is always the most effective strategy.
Best practices
Monitor your bounce messages closely, as even generic 'soft bounce' indicators hide valuable error codes.
Segment your iCloud audience and analyze engagement patterns to identify potential issues.
Ramp up sending to iCloud addresses gradually after periods of inactivity or significant list growth.
Verify that your SPF, DKIM, and DMARC records are correctly set up and aligned.
Regularly clean your email list by removing unengaged subscribers and invalid addresses.
Common pitfalls
Ignoring generic soft bounce messages, which can obscure critical underlying deliverability problems.
Sending to very old or unengaged iCloud segments, leading to low engagement and higher bounce rates.
Not monitoring your sending volume and frequency, especially sudden spikes that ISPs might flag.
Failing to adapt email content to align with recipient engagement and preferences, increasing spam likelihood.
Overlooking the impact of Apple's Mail Privacy Protection on traditional open rate metrics for overall list health.
Expert tips
Leverage DMARC reports to gain insights into your email authentication failures and overall deliverability to Apple domains.
Consider a warming-up strategy for new IPs or domains sending to iCloud to build positive sender reputation.
Implement feedback loops where available to quickly identify and remove subscribers who mark your emails as spam.
Test your email content for spam triggers before sending, especially for campaigns targeting iCloud users.
Regularly check your sending IP and domain against major blocklists (or blacklists) to ensure you're not listed.
Marketer view
Marketer from Email Geeks says that multiple reasons exist for a sharp increase in soft bounces from specific ISPs, including blocklisting or server downtime.
2022-05-30 - Email Geeks
Expert view
Expert from Email Geeks says that the term 'soft bounce' is often an internal classification by the ESP, and it may indicate that iCloud or its anti-spam vendor has implemented a spam block.
2022-05-30 - Email Geeks
Navigating iCloud's deliverability landscape
A sudden spike in soft bounces from iCloud email addresses points to evolving challenges in email deliverability, especially with ISPs that prioritize user experience and privacy. By understanding the nuances of soft bounces, recognizing iCloud's specific filtering mechanisms, and proactively managing your sender reputation, you can effectively diagnose and mitigate these issues.
The key lies in diligent monitoring, transparent communication with your ESP, and a commitment to maintaining a healthy and engaged email list. Adapting your sending strategies to align with modern email security standards will help ensure your messages consistently reach their intended recipients.
Apple. A low reputation score, whether due to high bounce rates, spam complaints, or low engagement, can cause your emails to be throttled or outright rejected. iCloud, like Google and other major providers, uses sophisticated algorithms to protect its users from unwanted mail.
