I found this feature very useful in one of the panel that I use. You can migrate the emails from other server to this. I think they are using imapsync in backend. Not sure though. So on the destination server, you need to specify the email details, like email id, password, IMAP Server and destination detail like email id. It seamlessly, transfers all the email. Please see the UI here https://prnt.sc/mmhMmxrxioCR. I request something similar to this. 🙂