Mimecast incident

TTP URL and Browser Isolation Errors on US and USB Grids

Minor Resolved View vendor source →

Mimecast experienced a minor incident on May 19, 2026 affecting United States Grid and United States B Grid and 1 more component, lasting 4h 28m. The incident has been resolved; the full update timeline is below.

Started
May 19, 2026, 01:59 PM UTC
Resolved
May 19, 2026, 06:27 PM UTC
Duration
4h 28m
Detected by Pingoru
May 19, 2026, 01:59 PM UTC

Affected components

United States GridUnited States B GridOffshore Grid (Threat Protection)

Update timeline

  1. investigating May 19, 2026, 01:59 PM UTC

    We are aware that some customers hosted on our US and USB grids may be experiencing issues accessing rewritten links, where URLs are being redirected through Browser Isolation and may result in an error. We are currently investigating this issue and will post updates here as they become available. All other Mimecast services are operating as normal.

  2. monitoring May 19, 2026, 03:05 PM UTC

    We have taken mitigation steps and believe we have resolved the issue that caused certain TTP URL links to be incorrectly redirected through Browser Isolation for customers. This was caused by TTP URL links being incorrectly categorized as unknown, resulting in clean links being redirected through Browser Isolation and, in some cases, returning an error. We are now seeing a sustained reduction in Browser Isolation requests and believe service should be returning to normal. We will continue to monitor performance closely and provide further updates as they become availab