Migrate servers and mailboxes? [closed]

view story

http://serverfault.com – I am moving a website from one hosting provider to another, and this of course means that I need to migrate all the mailboxes as well. Do I have to manually move all the old emails from one server to another, or will all the email clients "save" a copy of the old emails on each computer? UPDATE Pardon, the naivety - I hope this additional info helps: I'm doing this remotely, so I am not sure which email client(s) people will be using at the office, but I will need to be prepared for both POP and IMAP setups. Also, the server they currently have is on VPS.net (cPanel), and we are migrating (HowTos)