Use a custom email domain with Mail on iCloud.com

When you add a custom email domain on the iCloud+ Features page on iCloud.com, you can use any email addresses you create in Mail on iCloud.com.

Note: Custom Email Domain is not available in all countries or regions.

You can do any of the following:

Receive email for your custom address. The emails appear in your inbox, just like the mail from your iCloud Mail address and any aliases you create.
Send email from your custom address. You can select the address you want to send from when you write an email.
Change the name that appears in the From field when you send mail from a custom address.
Select a custom address as your default email address.

You can also use your custom addresses on any device that has Mail turned on in iCloud settings.

Helpful?

iCloud User Guide