XMAS
2
Hello and Welcome to the forums 
Yes, avast! can scan your MS Outlook Express 6 Email , using the Internet Mail provider 
But it depends what Windows you have - if your windows is NT based (WinNT, WinXP …) the Internet mail provider will scan your mail automatically , if you have older Windows (like Win95, Win98 …) you’ll have to run the Mail Protection Wizard , before avast! can scan your mail 