Migrate IMAP email to a new server can be a complex process, but here are some general steps you can follow:

1. Back up your existing email: Before you start the migration process, make sure to create a backup of all your existing email data. This will ensure that you don't lose any important emails in case something goes wrong during the migration process.
2. Set up your new email server: You will need to set up your new email server and configure it to work with your domain name. You may also need to create user accounts and email addresses for all the users who will be using the new email server.
3. Configure the email clients: You will need to configure the email clients on all the devices that access your email (e.g., desktop, laptop, mobile) to connect to the new server. This will involve updating the incoming and outgoing mail server settings.
4. Sync the mailboxes: Once the email clients are configured, you will need to sync the mailboxes. This process will copy all the emails from the old server to the new server. You may need to use a third-party tool to do this.
5. Verify the migration: Once the sync process is complete, you should verify that all the emails have been successfully migrated to the new server. You can do this by checking your email clients and making sure that all your emails are present.
6. Update the DNS records: Finally, you will need to update your DNS records to point to the new email server. This will ensure that all incoming email is delivered to the new server.

Keep in mind that the specifics of the migration process will depend on the email server software and email clients you are using. It's a good idea to consult the documentation for your specific software and seek professional help if needed.