Mark Unread email as Read in Exchange/Outlook

I have a vbscript that I would like converted to PowerShell. Currently the vbscript runs in outlook on startup. I would like to convert or create new powershell and run against all mailboxes from the backend so no end user interaction required. The script function is to search all emails in the active exchange mailbox older than date that is set in script and mark them as "read"