I have 4.8 Home on XP Pro SP3, and use Outlook.
I’m happy to say that Avast has been catching things inbound via email, but when I tell it to move to quarantine or delete permanently, the program returns an error message:
“Avast: unable to open the specified folder for infected inbound messages. Please make sure that the folder name is valid. The message cannot be moved. Error code is 80070057. Invalid parameter was passed to a function.”
This leaves me uncertain as to whether the infected email has been dealt with properly, or not.
Help or suggestions would be greatly appreciated.
Welcome to the forums, MiKemp. 
While I do not use Outlook and can not provide you with help, someone here who uses Outlook should be able to help you. Please be patient until someone does.