Should be no need to "pay" someone.
You simply need to make sure you plesk panel is set up to serve email on your provider for your domain.
Once you do that, you simply create the necessary user accounts (bounced, unsubscribe, site admin, system admin) with the necessary credentials. You will need to make sure you have your necessary DNS entries ready (DKIM, MTA info, etc) and once that is done you shoudl have no issues.... other than the simple fact your MTA IP may be black listed and you will have to jump through the hoops to get it cleared up.
You will need to use the credentials you created earlier (bounced, admin, system reply) to set up your accounts in the ACP of XenForo.