Unlimited SMTP Setup on cPanel

I need a fresh SMTP server configured and fully integrated with my existing cPanel account so I can push roughly 1 000–10 000 emails per day through Webmail without bumping into the usual sending limits. There is no current SMTP service in place, so the job starts from scratch: provisioning the server, linking it to my domain inside cPanel, and making sure every authentication layer—SPF, DKIM, DMARC, rDNS—is properly applied for strong inbox placement.

Once it is live, I want to be able to open Roundcube (or any default Webmail client that ships with cPanel) and send campaigns confidently, knowing throttling is no longer an issue. Please secure the server, tweak Exim or Postfix for high-volume performance, and leave me with clear, concise notes on how to add future domains or adjust limits if my volume grows.