Windows Live Mail (from MS Windows Essentials) is, like Thunderbird, free and is also available for Win8 as well as Win7.
But Outlook Express morphed into Windows Mail ( on my Vista machine ) and then Windows Live Mail ( on my Win. 7 machine ) neither of which are exactly like the original Outlook Express - which was the point of the original equiry.
Usual bleat - Outlook Express wasn't 'broke', so why fix it ? Leave the damned things ALONE ! Why are we 'old dogs' constantly having to learn new tricks, we're quite happy with what we have, thank you.