Move email/email account from iphone to computer

If it is not an IMAP account, the only way to have the POP account mails show up is if they are still stored on the server. If the iPhone has it set to delete mail from the server, they can't be unless he forwards them to himself. If they are still on the server (this is received mail only), once you set up the new computer and start the mail program, it would be recognized as a new mail client and would download the mail again. If it is an IMAP account, the mail folders would automatically sync when you set up the account on the computer because all of that information is stored on the server and is designed to by synced to multiple clients.