During the WWDC 2021 keynote, Apple announced news for Clouds and the iCloud + subscription service. One of the most interesting new features of the latter is the ability to create custom domain names for emails.
Through this new function we will be able to customize our iCloud email address with a custom domain name. Additionally, we will be able to invite family members to use the same domain with their iCloud mail accounts. At the moment, however, we don’t know if the Family Sharing feature is required to invite family members or we will be able to invite anyone.
With this feature, Apple could offer business and school emails with custom domain names on iCloud, becoming a direct competitor of Google and Microsoft. At the moment, however, Apple has not made any announcements on the matter, so it is plausible that it is a sort of block in this sense.