There is a way you can do that in an IMAP account by eg: “Ignoring the Yahoo sub folders you dont want to sync” on the server “by excluding each specific server folder” in the account diagnostics tab. So eM Client should then in Theory only sync the Yahoo Inbox.
See @Gary post in the following thread on that subject.
https://forum.emclient.com/t/imap-folder-subscription/37339/19