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Internet Exchange Frequently Asked Questions

Internet Exchange Messaging Server
Anti-Virus Module FAQ

Overview
The Internet Exchange Messaging Server Anti-Virus Module (both Enterprise and Workgroup versions) is a 32-bit multithreaded, stand-alone preprocessing module capable of performing concurrent virus scanning for MIME and non-MIME message attachments.  To minimize delay in message delivery, the Anti-virus Module is designed to create multiple threads for performing simultaneous virus scans, with each thread processing one message at a time. 

For each thread, the module determines what decoding method to use on each attachment based on the MIME headers of the MIME/RFC822 message.    If the attachment is embedded in a non-RFC822 message, either UUDECODE or BINHEX is used.   After decoding the attachment, an external virus scan engine is invoked by the module.   If a virus is found in a message, the engine either bounces the mail, copies the mail to a predefined location/folder, or deletes the mail (with the option to notify the postmaster after deletion) as configured by the user.    After all attachments have been scanned, the moodule returns to appropriate error code.

The decision on whether or not to run the Anti-Virus engine against a particular message is determined by the configuration of the Anti-Virus Channel Action Matrix.

Additional information related to the Anti-Virus engine can be found in the following documents: