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Why are messages being Deferred for reason 'Possible Outbreak' within the ESS or the Cloud Protection Layer?

  • Type: Knowledgebase
  • Date changed: 2 years ago
Solution #00006386

- The Barracuda Email Security Service
- The Barracuda Cloud Protection Layer

Barracuda Email Security Service (ESS) is a single service with thousands of domains. The 'Possible Outbreak' feature is not a per domain rule; it actually covers the entire service. If an email-sending entity sends out a message to thousands of people across our service, it may be picked up as a Possible Outbreak event. These are often false positives which will later go away. The sending server should get back a 4xx message for 'Possible Outbreak' and will retry sending the message at a later time. The ESS watches for this, and if the message is retried, it assumes it is legitimate and the Possible Outbreak delay is removed.

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