The program is supreme program to update outlook express to outlook, update outlook express to outlook 2010, update outlook express to ms outlook.Software will not allow users to import system DBX files or file.
First of all make a backup of all folders in case you make a mistake so you wont loose your emails. If you see there more than one folders (identities folder) then normally the older one has your old emails.
Right click to see which is older one and replace the contents of older identity folder to newer one. People - Please note that the coming update for Windows 10 users (1511) is also likely to uninstall Outlook Express.
Actually as I posted before you won't lose everything, only the address book, account settings and message rules.
Also the drag&drop of a file to be attached in a new message window doesn't work anymore in Windows 10 (maybe it's related to that Send-to function). Open your identities folder, identities folders are forders named somethidg like The path of these folders is "C:\Users\YOUR USER NAME\App Data\Local\Identities\" .
The emails are still in the Identity folder and easily could be retrieved. A kind request to OE developers: please bring back the Send-to function in Windows 10.