Major incident

Optimizely Service: Email Campaign Delivery Drops — NA Region

Affected: Campaigns

Current status of Optimizely Service: Operational — live Optimizely Service status

Timeline

1. Jun 17, 2026, 14:00 UTC
   investigating
   We are investigating an issue causing some email campaign messages to be dropped in the North America region. Some emails are still being delivered. Accounts using email campaigns in the region may be affected. We will update as we learn more.
2. Jun 19, 2026, 12:13 UTC
   investigating
   We are continuing to investigate this issue. We also have a support thread open with Sendgrid.
3. Jun 19, 2026, 19:02 UTC
   investigating
   We are still looking into this issue and will provide updates as they become available.
4. Jun 19, 2026, 19:51 UTC
   identified
   We have likely identified the root cause as a recent SendGrid change that introduced an incompatibility in header processing. We are sharing our findings with SendGrid and implementing a workaround to restore compatibility.
5. Jun 19, 2026, 21:50 UTC
   monitoring
   We have deployed a fix to unblock affected customers and are actively monitoring the system to confirm stability. We are also working with our email vendor (SendGrid) to put a more complete solution in place on their side. Please note: during the period when emails were partially dropped, we do not have a record of which individual recipients successfully received messages. As a result, if you choose to re-run an affected campaign (e.g., by sending it to a new campaign), some recipients may receive duplicate emails. We will provide a further update as monitoring continues.
6. Jun 19, 2026, 22:29 UTC
   monitoring
   We are continuing to monitor for any further issues.
7. Jun 20, 2026, 17:41 UTC
   resolved
   This incident has been resolved.

Updates as published by Optimizely Service (original).