Why were there delays to Apple domains in January 2024 and have they been resolved?
Michael Ko
Co-founder & CEO, Suped
Published 27 Jun 2025
Updated 17 Aug 2025
5 min read
In January 2024, many email senders, myself included, started noticing unusual delays when sending emails to Apple domains, such as @icloud.com, @me.com, and @mac.com. These were not typical bounce errors, but rather significant deferrals and timeout-like events that left us wondering about the root cause. The initial reports pinpointed the issue starting around January 16, 2024, UTC.
The situation created a wave of uncertainty among email professionals. Was it an isolated issue on our end, or was something larger at play with Apple’s mail infrastructure? The impact was immediately felt, with critical communications being held up, affecting everything from transactional emails to marketing campaigns. My team and I began a deep dive to understand what was happening.
This article details our findings, the insights shared by the email community, how the issue was ultimately resolved, and crucial steps you can take to mitigate similar problems in the future. Understanding these events is key to maintaining high email deliverability, especially when major providers like Apple experience service disruptions.
The emergence of delays
Initial reports indicated that emails were not outright bouncing, but rather experiencing timeout type events and connection rejections. This behavior suggested that Apple's mail servers were either overwhelmed or actively throttling incoming connections. We observed these delays across various customers, indicating it wasn't isolated to a single sender or infrastructure.
One of the most concerning aspects was the widespread nature of the problem. My internal monitoring showed that these issues weren't confined to a single outgoing IP address or data center. Both North American and European data centers were seeing these timeout events, strongly suggesting that the problem lay with Apple's mail infrastructure rather than our own systems.
The initial uncertainty led to many discussions within the email deliverability community. Senders were sharing similar experiences, confirming that this was a broader issue impacting various sending platforms. While some initially thought it might be related to a specific incoming IP address, further investigation by multiple parties pointed away from isolated incidents.
Technical insights and proposed causes
Through collective monitoring and data analysis, we identified specific Apple MX (Mail Exchanger) IP addresses that were primarily responsible for the connection rejections. This level of detail allowed us to narrow down the problem and confirm it was likely an internal issue on Apple's side, possibly due to overloaded servers or a configuration error.
A common theory circulating was the presence of an "angry server" or a specific set of servers within Apple's network that were behaving erratically. This kind of localized issue can cause ripple effects across an entire mail system, leading to the widespread delays we observed. It highlights how even a single misconfigured or overloaded component can severely impact deliverability across the board.
Type
IP Address
Primarily rejecting connections
17.57.154.33, 17.57.156.30, 17.42.251.62
Subsequently accepting messages
17.56.9.29, 17.57.155.34
Resolution and confirmation
Thankfully, the situation did not persist indefinitely. Within a day or two of the initial reports, we observed a significant shift in the traffic patterns. Connection rejections to the problematic Apple MX IPs began to drop dramatically, while accepted messages spiked on other, previously less active, Apple IP addresses. This indicated that Apple likely rotated their mail infrastructure, diverting traffic away from the affected servers and restoring normal delivery.
Swift action is key
While Apple did not issue a public statement regarding the specific delays, the observed changes in their mail routing confirmed that they were actively working to resolve the issue. The quick resolution, within hours of it starting, underlines the importance of internal system monitoring and agile response from major email providers to maintain service stability.
What to do if you face similar issues
Even when a deliverability issue originates with an inbox provider like Apple, having robust systems in place can help minimize impact and accelerate recovery. Proactive monitoring of your email deliverability metrics, including bounce rates, deferrals, and DMARC reports, allows you to detect anomalies quickly. Tools that provide real-time insights into your email stream are invaluable.
Beyond monitoring, strong email authentication (SPF, DKIM, DMARC) is foundational. While it might not prevent an ISP outage, it ensures your emails are correctly identified as legitimate, which can help them get processed faster once service resumes. A well-configured DMARC policy provides crucial visibility into your email ecosystem and can alert you to potential issues. If you are experiencing bounce errors from Apple domains, review your authentication.
Before a problem
Implementing these measures proactively helps build a resilient email program, reducing the impact of unforeseen network or service disruptions.
Monitoring: Establish continuous monitoring of deliverability metrics.
Maintain strong authentication (SPF, DKIM, DMARC) to bolster your sender reputation.
Continuously monitor your email deliverability metrics for anomalies and swift action.
Diversify your sending infrastructure if experiencing persistent issues with a specific IP.
Common pitfalls
Assuming issues are always on your end without investigating major ISP status pages.
Neglecting to monitor deliverability dashboards, leading to delayed issue detection.
Failing to engage with the email community for shared insights during widespread incidents.
Expert tips
Set up alerts for sudden spikes in deferrals or connection rejections to key domains.
Establish a clear communication plan for when deliverability issues affect recipients.
Regularly test your email delivery to various major inbox providers to catch subtle changes.
Marketer view
Marketer from Email Geeks says they started seeing delays to Apple domains around January 16, 2024, at 19:00 UTC, with many customers experiencing timeout-type events, suggesting a possible issue on Apple's side.
2024-01-16 - Email Geeks
Marketer view
Marketer from Email Geeks says they've seen other reports indicating similar delays to Apple domains, confirming it was not an isolated incident for one sender.
2024-01-16 - Email Geeks
Navigating future email delivery challenges
The January 2024 email delivery delays to Apple domains served as a sharp reminder that even the most robust email infrastructures can face unexpected challenges. While the specific cause wasn't publicly disclosed by Apple, the community's observations pointed towards an internal infrastructure issue, which was then resolved through changes in their mail routing.
For email senders, this event underscores the critical importance of continuous deliverability monitoring and maintaining strong email authentication. Being proactive allows you to quickly identify, diagnose, and adapt to such issues, ensuring your essential communications reach their intended recipients with minimal disruption, even when major service providers encounter problems.
Apple IP addresses. This indicated that Apple likely rotated their mail infrastructure, diverting traffic away from the affected servers and restoring normal delivery.
