Yes, it will work, that's how I did it a few months ago. But you will have to set the permission too. Also before copying anything, I made sure I had created accounts for every client and did them one by one. Not sure if that was necessary, just wanted to be safe and avoid uncomfortable phone calls with clients who lost emails.
Also if you want to transfer the passwords, you can do that too through the Postfix table on MySQL. Let me know if you need more information on that.