Outage in Klaviyo
Yahoo PH01 Block — Email Bounces to Yahoo/AOL Recipients
Resolved MinorIncident Report
Summary AI Generated
Starting at 2:30 AM ET on July 2, 2026, a subset of Klaviyo customers experienced elevated email bounces to Yahoo and AOL recipients due to a PH01 policy block within Yahoo's infrastructure. The issue affected email deliverability for approximately 2.1 hours. Yahoo resolved the block by 10:17 AM ET, and customers were cleared to safely resend to affected bounced recipients.
Starting at 02:30AM US/Eastern on 07/02/2026, a subset of customers are currently experiencing an increase in bounced emails to Yahoo and AOL recipients with the reason of "554 Message not allowed - [PH01] Email not accepted for policy reasons.".
Our Engineering and Deliverability teams are actively investigating and working with Yahoo to resolve the issue. We do not recommend resending to those bounced recipients at this moment in time.
Components affected
Klaviyo Email DeliverabilityTrusted by 1,000+ teams
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Latest Updates ( sorted recent to last )
RESOLVED
23 days ago - at 07/02/2026 02:17PM
The block within the Yahoo infrastructure that resulted in these elevated bounces has been resolved. Customers can safely resend to bounced recipients from this time period. This incident has been resolved.
INVESTIGATING
23 days ago - at 07/02/2026 12:17PM
Starting at 02:30AM US/Eastern on 07/02/2026, a subset of customers are currently experiencing an increase in bounced emails to Yahoo and AOL recipients with the reason of "554 Message not allowed - [PH01] Email not accepted for policy reasons.".
Our Engineering and Deliverability teams are actively investigating and working with Yahoo to resolve the issue. We do not recommend resending to those bounced recipients at this moment in time.
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