If you have a sample still, put it in the chest, User Files, section, File, Add and use the navigation to import the file. Once in here you can right click and select email to Alwil software, this doesn't require you zip and password protect the file that is done by avast. It won;t hurt to send it again.
This still gets sent to the same address, once there it is filtered to a different mail box as a sample submitted through the avast program. I can only assume that this will receive a slightly higher priority. Over 4000 emails per day are received at the virus at avast address.