If you access your web based email account via an internet browser, your PC is protected by other Avast shields.Enabling JavaScript and cookies in your web browser
Scanning applies only to messages sent or received using a mail management software (email clients, such as Microsoft Outlook or Mozilla Thunderbird). Mail Shield: scans your incoming and outgoing email messages in real-time for malicious content such as viruses. Web Shield: scans data that is transferred when you browse the internet in real-time to prevent malware, such as malicious scripts, from being downloaded and run on your PC. Behavior Shield works by detecting and blocking suspicious files based on their similarity to other known threats, even if the files are not yet added to the virus definitions database. Behavior Shield: monitors all processes on your PC in real-time for suspicious behavior that may indicate the presence of malicious code. If malware is detected, File Shield prevents the program or file from infecting your PC. The Core Shields are: File Shield: scans programs and files saved on your PC for malicious threats in real-time before allowing them to be opened, run, modified, or saved. By default, all Core Shields are enabled to provide optimal protection. Core Shields displays the main protection components in Avast Antivirus.