Clam win 
ClamWin is a free antivirus solution for systems. It is an open-source free software. This software also offers good basic protection without upgrading to its paid antivirus packages. It automatically updates the database of the virus when connected to the internet. It will try to establish a connection with the help of a server when it fails to download any updates for the first time. Though it is a basic version, it is very effective. There will be a small balloon tip that will appear on the taskbar icon which indicates the status of completion of the process of updating. 
Why you must get it: 
ClamWin has some free tools that provide some basic functionalities. Some features of ClamWin are the schedule scanning, removing the virus that is infected in the attachments automatically, and it also regularly downloads the updated database of the virus. It has a fixed virus database update. Clam Win can integrate directly into the Microsoft Outlook email client and Windows Explorer. This makes it easy to send individual files, folders, and email attachments for inspection.