At 9.30pm PT on Tuesday Aug 9, 2016, Barracuda Networks issued a virus definition, 18.104.22.16843, which incorrectly classified .doc files as viruses (Win.Exploit.CVE_2016_3316-1). This means that all emails with .doc filetype attachments were blocked as they were identified as viruses. There was an in between definition version 22.214.171.12450 that affected the virus scanning functionality, but those impacted had emails that were deferred for a short period of time, with no loss of emails. By 2.57am PT on Wednesday Aug 10, 2016, virus definition version 126.96.36.19954 or higher, removed the signature from our database, and fixed all issues.
All ESGs with auto-update enabled for Energize Updates should have the update definitions pushed out. Please go to Advanced -> Energize Updates to check which virus definition you have. You can force the update of the virus definitions manually, if you are not seeing a version number of at least 188.8.131.5254 or higher.
Customers who believe they may have been affected by the virus definition should search the Message Log for Word Documents of format .doc only (not .docx) during that time frame and ask the sender to retry sending the message. We apologize for the inconvenience.