LISTSERV checks only the time stamp of the database files. It does not check Windows Update to see when the last time the files were updated. If/when the database file is determined to be five days old, LISTSERV begins notifying the non-quiet postmaster(s) to alert them to a possible problem.


In this case you should do the following:


Windows:  Check Windows Update to make sure that it is running. If it is, and if the report at the bottom of Settings -> Update & Security -> Windows Defender indicates that the signatures are up to date, then the warning can be ignored.  Otherwise you will have to investigate why the Windows Defender signatures aren't updating normally.


Other Platforms using AVS:  Check that the AVS is up and running and can be reached from your primary LISTSERV server by email.  If it is, and if it reports that the signatures are up to date, then the warning can be ignored.  Otherwise troubleshoot as above.