Over the weekend we tested and perfected a new method for managing archive embedded dangerous content. During the deployment of the new software some archives were improperly classified as dangerous and archives (.zip, .arj) removed. That issue has been solved as of Sunday evening.
As a point of reference, ExchangeDefender does not allow executable attachments (.exe, .bat, .com or .pif) in either standalone or archived mode. That means even if you zip the file up it will be picked up by a scanner. If you zip a zip file, the system will reject to process it. This has been our long standing tradition of not allowing dangerous content through the network because virus scanners sometimes do not react as quickly to the rise in malware and our responsibility is to protect our customers. If you need a dangerous attachment really bad, for the safety of the less IT savvy people in your organization, please try to find alternate means such as a web sharing tool or a freemail account.
We have also addressed this need in ExchangeDefender 4.x which is scheduled for August 19th.