What version of avast are you using, I assume the free home version ?
Also what type of scan are talking about, on-access or on-demand ?
On-Access resident scanner detections:
These advanced automated options are only available in the Pro version.
You only have a limited option in the Home (free) version, to send the infected file to the virus Chest (silent mode, with general answer no, see below).
My own feeling on this is you should use the default interactive action. This way you know exactly what is going on with your system. If you are getting so many warnings, that you want to automate this process, I believe you should review your security practice - filter emails at source, delete from server rather than download them, review the sites they visit, etc.
See the avast help file, Resident Protection: Standard Shield Provider Settings - "Advanced" Page.
Click on Standard Shield and then on Customize.
Go to Advanced tab and select Silent Mode and the General answer No.
