Allow User to move folders between accounts
The purpose of this feature is to make it easier for users to migrate between email providers , such as going from Google to Office 365, or similar use case. For example: A user moves their DNS domain to the new provider, updates DNS records, and now wants the same email and folders in the new mailbox. Currently, they need to manually create destination folders, select emails in the old folder, and use the transfer to menu option to initiate the transfer,
My idea is to let them click and drag the folder from the old mailbox to the new mailbox, and then go get some coffee while they wait for it to complete
A progress indicator showing active transfers and their progress would be nice as well. if you have every used VCenter for VMware, you can see every operation and it's status. eg power off system, move system to another host, etc.

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Piermaria Maraziti commented
I did migrate two times my mail account and I would suggest not to do it in this way. It's error prone and bandwidth consuming (however I was moving tens of thousands of messages).
My solution was using imapsync (a python script). -
Don commented
+1. Apple Mail already supports this. I use it to move mail to a local instance of DoveCot to "archive" old mail.