Lettermint incident

[Blocklist] Broadcast IP blocked with Outlook OLC

Minor Resolved View vendor source →

Lettermint experienced a minor incident on August 12, 2026, lasting —. The incident has been resolved; the full update timeline is below.

Started
Aug 12, 2026, 08:13 AM UTC
Resolved
Aug 12, 2026, 08:13 AM UTC
Duration
—
Detected by Pingoru
Aug 12, 2026, 08:13 AM UTC

Update timeline

  1. investigating Aug 11, 2026, 08:03 AM UTC

    Status: Investigating We’ve identified that one of our outbound broadcast IP addresses have been blocklisted, affecting email delivery for some customers. The team is currently investigating the cause and working on delisting the IP. In the meantime, the IP address has been suspended and will not be used until the issue is resolved. This does not affect other IPs in the pool nor transactional routes. If you have seen a hard bounce because of this, you can safely reactivate the recipient from your suppression management. Affected components Outgoing (Broadcast) (Degraded performance)

  2. identified Aug 11, 2026, 08:24 AM UTC

    Status: Identified We have identified the source of the listing and are actively remediating the issue. We will keep monitoring the situation. Our sincere apologies for the inconvenience. Affected components Outgoing (Broadcast) (Degraded performance)

  3. resolved Aug 11, 2026, 12:19 PM UTC

    Status: Resolved We have fully removed the affected IP address from active sending and traffic has been rerouted across our remaining broadcast infrastructure. Email delivery is operating normally again. The affected IP will remain out of service while we continue working with Microsoft on the block. As this no longer impacts active sending, we are marking this incident as resolved. Transactional routes and other broadcast IPs remain unaffected. Affected components Outgoing (Broadcast) (Operational)