Hi, Since my old email server is old, so, I changed to a new email server. Both are running isp 18.104.22.168. some of my clients will keep emails on server even the downloaded emails to their outlook. The problem I not face to is, the server move successfully. All clients old emails also moved to the new server, but their outlook will download all old emails again evev I manually marked the emails as read in server. It really make me and my clients crazy because some of them keep years of emails. How can I solve it? Thanks!!