Use a custom email domain in Mail on Mac
When you subscribe to iCloud+, you can add up to five custom email domains to your iCloud Mail account. Then, you can send and receive mail in the Mail app on your Mac, iPhone, iPad, iPod touch, in your Mail account on iCloud.com, and in the email app on a Windows computer.
You need to have a primary iCloud Mail address before you can add a custom email domain on your Mac. See Create a primary email address for iCloud Mail in the iCloud User Guide.
To learn more, see Personalize iCloud Mail with a custom email domain and share with others in the iCloud User Guide.
Note: Make sure you’re signed in with the same Apple ID on each device. If you have devices where you’re not signed in with your Apple ID or that have the Mail feature turned off, your custom email domains and mail aren’t available on those devices.
Send and receive from a custom email domain
Choose Apple menu
Click iCloud on the right, then click iCloud Mail.
Turn on iCloud Mail (if it’s not already on).
Click Options next to Custom Email Domain, then click Continue to sign in to iCloud.com.
Click Manage below Custom Email Domain, then follow the onscreen instructions to add, purchase, or manage your domain.
