Protector is an alternative approach to blocking Email attachment Viruses at the MailServer. It does not actually scan for viruses, but rather, quarantines any attachments that may contain malicious code. It does this by examining the payload of an attachment rather than paying attention to the FileType declared in the header of the attachment. It also examines the contents of compressed archives.

It has been written with SendMail in mind, but is reported to run on other MTAs as well.