I have a question regarding the database location. I was wondering if it could be moved to a Dropbox folder, and then use that to populate another installation of the program on my laptop. Thereby syncing everything between my PC & laptop.
It is not possible to store the database on a Cloud drive.
As long as your account in eM Client is setup as IMAP, then you will have the exact same messages on any computers and in any email clients that are connected to the same email account.