Zoho Mail - Custom Domain Help?

Zoho Mail - Custom Domain Help?

Ok, so after a week of trying to figure this out, I've finally got my MX settings set to Zoho (domain is still registered with 1and1.com) and I added an email address using Zoho Business.

But then went I went to Zoho Mail, my new email address at my domain was there...but what happened to my free Zoho email address?

By using my own domain with MX pointed to Zoho, did I just create a NEW email address or just an alias for my old free zoho email address?

I guess the real question is: Why did I just go through all that trouble of transferring my MX records to Zoho? What is the benefit of having Zoho host my email as opposed to 1and1.com?

This is extremely confusing.