SparkPost incident
Elevated hard bounces for Apple private relay recipients (privaterelay.appleid.com)
SparkPost experienced a minor incident on August 27, 2026 affecting Mailbox Provider Service Interruption, lasting 4h 53m. The incident has been resolved; the full update timeline is below.
Affected components
Update timeline
- identified Aug 27, 2026, 04:51 PM UTC
Beginning 2026-08-26 around 23:00 UTC, we are observing a significant increase in hard bounces for messages sent to recipients at privaterelay.appleid.com, the relay domain used by Sign in with Apple. Affected messages are rejected by Apple's mail servers with the SMTP response 550 5.1.1 user not found. Our investigation confirms this originates upstream at the receiving mailbox provider, not within our platform. Delivery to all other domains, including icloud.com, me.com, and mac.com, remain unaffected and are performing normally. A substantial share of the affected addresses delivered successfully as recently as 2026-08-26, indicating the rejections do not reflect genuine invalid recipients. Impact: Because these are hard bounces, affected recipient addresses may be automatically added to your suppression list, which will prevent future sends to those recipients even after the underlying issue is resolved. Action required: None at this time. We recommend you do not attempt to manually clean or re-import affected suppression entries while the issue is ongoing. We are working directly with Apple on a resolution. Once resolved, we will remove suppression entries created by this event and will confirm the scope and timing in a follow-up update. We will post our next update within 4 hours or sooner if the situation changes.
- identified Aug 27, 2026, 06:03 PM UTC
We continue to see elevated 550 5.1.1 user not found hard bounces from Apple private relay. Once resolved on the provider's side, we will automatically remove Apple Private Relay suppression entries created by this event.
- identified Aug 27, 2026, 07:10 PM UTC
We have started to see recovery of the Apple private relay domain. We will continue monitoring for the next 60 minutes to confirm full recovery. Our team is actively working on automatically removing any suppressions that were created by this event. We anticipate the cleanup to be completed by 4PM EDT.
- monitoring Aug 27, 2026, 07:28 PM UTC
We have seen recovery of the Apple private relay domain to pre-event bounce levels. Our team is actively working on automatically removing any suppressions that were created by this event. We anticipate the cleanup to be completed by 6PM EDT.
- resolved Aug 27, 2026, 10:56 PM UTC
The Apple bounce levels have maintained at pre incident levels during our monitoring phase. Our clean up of the bad suppressions has finished. This incident is resolved.