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Klaviyo: Yahoo PH01 Block — Email Bounces to Yahoo/AOL Recipients

MinorStatus: resolvedStarted Resolved (2.0 h)2 updatesstspg.io (opens in new tab)

Affected components: Email DeliverabilityEmail Sending - Email Deliverability

Timeline of updates

  1. investigating

    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.

  2. resolved

    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.

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Impact, status and times are the vendor’s own, as last archived. View on stspg.io (opens in new tab).

Cite this

Status incident (vendor impact label: minor) posted by Klaviyo, started 2026-07-02 12:17 UTC, resolved after 2.0 h, 2 update(s).

Title
Yahoo PH01 Block — Email Bounces to Yahoo/AOL Recipients
Vendor
Klaviyo
Date
URL
https://rewindex.com/company/klaviyo/incidents/0s66874fm4zc

Klaviyo profileRecent Klaviyo incidentsAll outages on July 2, 2026Klaviyo in July 2026MarkdownJSON