I'm trying to understand the difference between Private Domain and Verified Domain in Salesforce Marketing Cloud.

I get that a Private Domain offers full DKIM, SPF, and DMARC authentication for your custom domain, which can significantly improve email deliverability.

However, I've noticed that Constant Contact allows you to add these authentication records yourself. So, is a Private Domain strictly necessary in Salesforce Marketing Cloud, or can I achieve similar results by manually adding the authentication records?

I'd appreciate any insights or experiences you might have on this topic. Thanks in advance!