I recently moved my Mail folder to another hard-drive to reclaim main hard-drive space,but can't get things to perform correctly

Hello, Specifically the this involves Local Folders sub-folder I'd labeled "Outlook Express Import" after having switched from Outlook Express *several* years ago ! This became my place to save (archive) any newer and the older under their own sub-folders labeled for the authors of the Emails. However, after moving the Mail folder to the other hard-drive things are not working correctly at all! Is there ANY way to to create the mention function I wish to resurrect??? Many thanks in advance.... Mark C. Hein