It monitors the folder where the received and sent files are stored. Whenever the content of the folder changes (a new file appears, a file is modified, etc.), avast! immediately performs a scan. On Windows NT, 2000, and XP operating systems, all the files modified by the communication programs are scanned (even outside of the mentioned folder).
Note: The protection of mIRC program is available on Windows NT, 2000, XP, and 2003 only.