In terms of both network security, which includes IM, P2P, network and Web protection and the resident protection, Avast! scans your incoming and outgoing mail. It does not work together with your e-mail program, but works on the lower, protocol level with POP3, SMTP, IMAP4 and NNTP, which means that you are also protected from the malware that can arrive with your newsgroup subscriptions. The program ensures protection by going one level deeper in the user space and works with the instant messaging, peer-to-peer, e-mail and newsgroup protocols.
The users may think that the instant messaging is safe. It is, to some degree, correct. It is not likely that you will be infected by a virus just by sending text messages. However, today’s instant messaging programs offer far more features than sending messages, including file sharing. In addition to instant messaging, there are also the peer-to-peer programs that Internet users are sending/receiving files to/from eachother, which also needs protection.
Network and Web Shields together form the online protection. Network shield takes care of the Virii and Trojans in the wild (the ones that are not identified and spreading) and protects the computer as a lightweight firewall program against intrusion. Web shield, on the other hand monitors all the HTTP traffic and provides a countermeasures against adware, spyware, dialers etc.
The program’s nice part with the web and network scanning is that, it checks out the traffic real-time. In other programs, the incoming traffic is first cached (saved on the computer), analyzed and sent back to the system. Avast! does this on the fly and does not cache the traffic. You can expect a little memory usage here. In my tests, I have noticed the memory use between 5% and 18% when idle. You can safely assume this as 8% - 10%, which is good for an all-in-one program.