Creating a business email for free is very simple..
All you need to have is a custom domain name with access to create
A record
Txt record
Dkim record
Then goto zoho.com/mail
Create a free tier account which gives 1 professional business email with 5 users allowed..
Then create the email address you want..
Goto your domain account add those records as asked by zoho..
When done you will have a professional business email up and running for free..