This section explains how CommuniGate Pro can employ External Filter programs to scan messages. This feature is used to implement virus protection and content filtering.
The CommuniGate Pro Filters provide a much more solid solution than various stand-alone SMTP-based "mail scanners":
External Filters run alongside the CommuniGate Pro Server. They do not deal with message transfer protocols. Instead, the CommuniGate Pro Server passes them a message file right before the message is being enqueued into module queues. As a result, all messages can be scanned, not only the messages sent via a particular mail transfer protocol.
If the CommuniGate Pro ENQUEUER is configured to use several processors (threads), several messages can be scanned simultaneously. As a result, long messages that require several seconds of scanning time do not stop the message flow.
The third-party Plugins distributed by CommuniGate Systems usually require an additional License Key. Several Plugins are currently available.
The Helpers section specifies the information about the External Filters protocol. Read that section if you plan to design a new Plugin.