??? sorry I have no idea what you’re talking about, at least concerning Avast. For the rest, seems that your contact list has been hijacked. Oh yeah, if you got Avast prompting you about deleting files (or send them to “chest”, ie quarantine them), that already means that your system is badly infected, especially if like you’re saying it happens on a regular basis. It should never happen… (on a clean system).

This said unless you give more details, how you’re getting and sending mails (email client.web interface…), details found in Avast alerts, it’s gonna be difficult to help.