What are the email deliverability impacts of Apple's Sign-in with Apple private relay service?
Matthew Whittaker
Co-founder & CTO, Suped
Published 25 Jul 2025
Updated 19 Aug 2025
7 min read
Apple's Sign-in with Apple service, along with its Private Relay feature, introduced significant changes to how users interact with online services and, by extension, how email communications are handled. Designed with user privacy at its core, these features provide a layer of anonymity that shields a user's real email address from third-party applications and websites.
While beneficial for user privacy, these innovations present unique challenges for email deliverability and sender reputation. Understanding these impacts is crucial for anyone involved in email marketing or communication to ensure messages reach their intended recipients without inadvertently triggering spam filters or being silently dropped.
Understanding Apple's private relay service and its email forwarding
When a user opts to use Sign-in with Apple, they can choose to generate a unique, random email address, typically ending in @privaterelay.appleid.com. This address acts as a forwarding service, relaying emails to their actual email inbox. This masking mechanism ensures that the user's personal email remains private and protected from potentially unwanted solicitations.
A critical aspect for senders is that users retain full control over this forwarding service. They can disable it at any time directly from their Apple ID settings. When this forwarding is turned off, emails sent to the @privaterelay.appleid.com address will no longer reach the user's actual inbox. This can lead to a significant challenge for marketers because, unlike a traditional unsubscribe, senders might not receive an immediate or explicit notification.
The primary impact of this user control is on bounce rates and overall email deliverability. If Apple decides to swallow (silently drop) emails instead of generating a bounce message when forwarding is disabled, senders are left in the dark. This lack of feedback makes it incredibly difficult to maintain a clean email list and ensure messages are consistently delivered. You can find more information about why emails to these addresses might go to spam here.
This silent failure can lead to inflated active subscriber counts and a false sense of engagement. Senders might continue sending emails to addresses that are no longer forwarding, wasting resources and potentially harming their sender reputation in the long run. Understanding this mechanism is key to adapting your email strategies.
Technical considerations for email deliverability
A critical technical requirement for sending emails to @privaterelay.appleid.com addresses is the proper registration of your sending domains with Apple's Developer Portal. Failing to register all source domains or email addresses used to send messages to these relayed addresses will likely result in a bounce message. This is a common pitfall that can immediately impact your deliverability.
Beyond registration, the impact on bounce rates is multifaceted. While some sources suggest that disabling forwarding could lead to hard bounces, there's also the possibility of silent rejections where Apple simply stops forwarding emails without notifying the sender. This makes it challenging to pinpoint exactly why an email isn't reaching the inbox. Understanding what it means if emails to these accounts are soft bouncing is important.
Sender reputation is closely tied to bounce rates and engagement. A high bounce rate, even if not immediately visible through direct bounce notifications, can negatively affect how mailbox providers perceive your sending domain. While Apple's private relay system aims to prevent abuse, it also means senders need to be more diligent in monitoring overall deliverability metrics and user engagement signals.
Important: Register your sending domains
To successfully deliver emails to @privaterelay.appleid.com addresses, you must register your sending domain(s) within the Apple Developer Portal. This step is non-negotiable for ensuring your emails are not blocked or bounced by Apple's relay service. Proper configuration is essential.
Impact on email marketing and data insights
Apple's privacy features, especially Mail Privacy Protection (MPP) introduced with iOS 15, significantly impact how marketers track email engagement. MPP preloads email content, including tracking pixels, when an email is received, masking the user's IP address and artificially inflating open rates. This means that traditional open rate metrics are no longer reliable for Apple Mail users.
The masking of IP addresses through Private Relay also means that geographic location data derived from email opens becomes less accurate or completely unavailable. This impacts segmentation strategies that rely on location-based targeting. Furthermore, IP warmup strategies might need adjustment if a significant portion of your audience uses Apple Mail.
For marketers, the key takeaway is to shift focus from unreliable open rates to more robust engagement metrics, such as clicks, conversions, and direct responses. This requires a re-evaluation of how campaign performance is measured and optimized.
The challenge of identifying inactive users becomes more pronounced. Without clear bounce signals or accurate open data, it's harder to determine which @privaterelay.appleid.com addresses are truly engaged. This necessitates a greater reliance on click-through rates and website activity to gauge subscriber interest and manage list hygiene effectively. The overall goal is to prioritize genuine engagement over vanity metrics.
Strategies for maintaining email deliverability
To mitigate the deliverability impacts of Sign-in with Apple and Private Relay, a multi-pronged approach is recommended. First and foremost, ensure that all domains used for sending emails to @privaterelay.appleid.com addresses are properly registered in the Apple Developer Console. This foundational step is non-negotiable for successful delivery.
Secondly, implement robust bounce handling and list hygiene practices. While Apple might not always provide explicit bounce messages, you should still monitor any bounce types you receive from these addresses. Regularly review engagement metrics beyond opens, such as clicks, conversions, and website activity, to identify inactive subscribers. Consider a re-engagement strategy for low-activity users before segmenting them out.
Third, prioritize content quality and user engagement. Highly engaged subscribers are less likely to disable email forwarding. Focus on sending relevant, valuable content that encourages clicks and interactions. This proactive approach strengthens your overall sender reputation and reduces the likelihood of emails being marked as spam or blocked (or blacklisted) by various providers, not just Apple.
Finally, ensure your email authentication protocols—SPF, DKIM, and DMARC—are correctly configured and maintained. Strong authentication is a baseline requirement for all legitimate senders and signals trustworthiness to mailbox providers, including Apple's Private Relay service. Proper configuration of DKIM and other records is crucial for ensuring that your emails are seen as legitimate and not spoofed.
Traditional email approach
Direct address: Real email addresses are collected, providing direct contact.
Open tracking: Reliable metric for engagement and list hygiene.
IP data: Used for geographic segmentation and reputation analysis.
Apple's private relay service
Masked address: Random @privaterelay.appleid.com addresses are used.
Open tracking: Unreliable due to Mail Privacy Protection preloading.
Bounce feedback: Can be silent (no bounce message) if forwarding is disabled.
IP data: Obscured, limiting geographic insights.
Views from the trenches
Best practices
Always register all sending domains with Apple's Developer Portal, it is a crucial setup step to ensure emails are delivered through Private Relay.
Shift focus from open rates to click-through rates and conversion metrics to gauge true user engagement and adapt to Mail Privacy Protection.
Implement robust bounce handling and list hygiene to identify and remove inactive addresses, even if direct bounce feedback is not always provided.
Common pitfalls
Failing to register sending domains with Apple, resulting in emails being blocked or bounced by the relay service.
Over-reliance on open rates as a key performance indicator (KPI) due to the artificial inflation caused by Mail Privacy Protection.
Ignoring silent rejections (swallowed emails) which can lead to sending to inactive addresses and negatively impacting sender reputation.
Expert tips
Use engagement metrics like clicks and conversions to identify truly active users.
Review sender reputation regularly, as obscured bounce feedback can hide deliverability issues.
Segment your audience based on behaviors you can track reliably, not just email opens.
Marketer view
Marketer from Email Geeks says that users can remove themselves from receiving communications without the sender knowing, creating a challenge for list management.
2019-10-24 - Email Geeks
Marketer view
Marketer from Email Geeks says that it is difficult to discover that an address is no longer active only by seeing multiple bounces from a user.
2019-10-24 - Email Geeks
Adapting to Apple's privacy-focused email landscape
Apple's Sign-in with Apple private relay service undeniably reshapes the email deliverability landscape by prioritizing user privacy. This shift means senders can no longer solely rely on traditional metrics like open rates or expect clear bounce notifications for every delivery failure.
Adapting to this environment requires a strategic pivot towards more robust engagement metrics, diligent list hygiene, and unwavering commitment to proper domain registration and email authentication. By embracing these changes, email senders can continue to achieve high deliverability and maintain a strong sender reputation in a privacy-centric world. The future of email success lies in proactive adaptation and understanding these new privacy paradigms.
Apple Developer Portal. This step is non-negotiable for ensuring your emails are not blocked or bounced by Apple's relay service. Proper configuration is essential.
