If you use iCloud then you have an iCloud email address username@iCloud or firstname.lastname@example.org. Using a custom email domain would allow me to use one of my domains mothsoftware.com or beatrixwillius.de to send out the emails with iCloud.
TidBits has a blog article on how to set up the custom domains which I won't repeat here. I remember doing setting changes as described in the article for a custom domain with Gmail which wasn't really fun. If you screw up somewhere it just doesn't work. It's more something that a system admin can do and not a "normal" email user.
What are the benefits and the drawbacks of using such a custom domain?
Benefits of using iCloud with a custom email domain
- You can use the https://www.icloud.com to access your email.
- Supposedly using a custom domain email address looks more professional than an iCloud address. I get emails daily. It doesn't matter to me at all which domain a user uses. Only hotmail.com and yahoo.com tell me that the users might be a bit older.
Drawbacks of using iCloud with a custom email domain
- iCloud now and then vanishes email.
- You have to use macOS 12 Monterey, iOS 15, and iPadOS 15 AND iCloud+.
- All email addresses of the domain have to use iCloud and not just one email.
- The number of email addresses per domain are limited.
- There is no simple way to migrate your existing emails. Of course, you could use Mail Archiver to archive your old emails. You could migrate your emails manually (which is going to suck). Or you could use Mail Archiver to migrate existing emails. But even with Mail Archiver this isn't going to be fun.
I know that GSuite is used by a lot of companies. With GSuite the whole email ecosystem is outsourced to Gmail. As a company I wouldn't trust Gmail at all. But saving money is always more important. But you can't use iCloud's custom domains for companies because the number of emails is limited.
For now custom domains for iCloud seem like a small test. Is Apple going the way of Gmail?