At least 2 GB of free space (additional space required for virus definition caches and quarantine storage).
The Ultimate Guide to Avira Antivirus Pro 15.0.37.326 Full: Advanced PC Security Explained
: Scans email attachments and incoming traffic to prevent email-borne malware.
Avira Antivirus Pro relies on a combination of local signatures and cloud-based analytics to stop malicious code before it executes.