If I open emclient, all emails get synced. I work with the emails, and then I minimize emclient. During that time, a bunch of new emails arrives, but the view is still stuck on the emails that were previously in the inbox.
eM Client shows new mail notifications when the mail client is minimised so you don’t miss new email, but It is by design that your position in the message list for that folder is remembered until you restart the application as @Gary advised in his post in the following thread on that feature request.
However you can put in a Sleekplan suggestion “to vote for that idea” via the following page.