Due to service errors caused by the recent Kakao IDC fire, various services are not working properly.
See related articles
https://www.soonsoon.co/think/801/
Among these, one of the services that many people find inconvenient and for which recovery is slow is the following email service; as of Monday, October 17, 2022, at 6:00 PM, the situation remains unrecovered.

Actually, this can be a very big problem, as it can be critically applied when conducting business or exchanging information via the following email.
Actually, I was using "Naver Smartworks" based on the following email and connecting a custom domain just a month ago, so it really felt shocking.
역시 다음 스마트 워크 서비스도 현재 시점으로 접속이 제대로 되고 있지 않다.

It seems that services centered on paid users are being restored first, while services centered on free users are being restored one by one, albeit late.. Fortunately, in my case, I had already migrated to an Apple Mail based on iCloud, so there is no issue with my business, but.. it feels very, very terrifying.
So, to help others, I am sharing the following content.
Just seven years ago, there were many free email services that allowed users to directly match and use their own domains, such as Google and Naver, but as of 2022, it is known that Naver Smartworks was the only service available in Korea.
And Kakao removed Kakao Next Mail login as of October 1st and attempted to unify services under Kakao, but this unification process was not smooth and felt somewhat shoddy, so I started looking for other solutions.
In conclusion, if you are considering connecting a custom domain for business, I recommend using a paid service. If I have the opportunity in the future, I will summarize it again, but Google offers a paid email service called Workspace that allows you to change and use your domain for about 6,000 KRW per month.

For Naver, a relatively more affordable premium email is offered under the name Smartworks, starting at 3,000 KRW per month.

Aside from these, there are various paid email services. Although we understand the situation following the Kakao incident, free users are not eligible for compensation and are not a priority in the event of an outage. Therefore, if you are operating a business, it is recommended to use an enterprise-grade email system, even if it requires payment.
However, individuals and startups may find even these low costs burdensome. For groups that are not quite ready, the cost of smart mail is often per person, so they look for free services to save money. But as mentioned earlier, there are currently almost no free domain email services left, or only overseas services remain that are difficult to verify for stability.
However, by utilizing the iCloud mail settings introduced today, you can use a custom email for your personal domain.

https://support.apple.com/ko-kr/guide/icloud/mm0e4339d289/icloud
However, this service is not free, and users using the iCloud+ service can use it for free, so strictly speaking, it should be considered a paid service.
Available starting from the 50GB plan, billed at 1,100 KRW per month. Of course, it's a bit ambiguous to call it an enterprise email service.. but if you just consider cost-effectiveness, it's quite excellent.


The setup is very easy and simple.
Creating an iCloud email address.
https://support.apple.com/ko-kr/guide/icloud/mmdd8d1d47/icloud
If you have obtained an iCloud email address, proceed to the following account settings screen.
https://www.icloud.com/settings/
Then, click the "Manage" button in the "User Settings Email Domain" menu at the bottom.

Then, the domain addition screen appears as shown below. Currently, I have already connected the soonsoons.com email.

It is said that you can connect up to three custom email domain addresses to a single iCloud email account. Use "Add a domain I own" at the bottom or tap "Buy a new domain" to enter the domain information.
When you click to purchase a domain, it seems to be linked through the Cloudflare service, not provided by Apple.

If connecting an existing domain, you can decide whether to use it personally or within an organization as shown below.

I am currently in the process of moving my main domain from soonsoons.com to soonsoon.co, and for the future members, I will select myself and others to proceed with the process.
If you already have an email address using that domain, simply add it; if you are setting it up for the first time, select “No email address.” If you have contacts who will be using the domain for their email addresses, click the Add people button to send them an invitation.

Next, you must enter the following DNS information at your domain registrar.
Since the method for entering DNS records varies slightly by registrar, if you get stuck here, please contact your registrar. There don't seem to be any special issues.
MX:
Type MX
Host @
Value mx01.mail.icloud.com.
Priority 10
MX:
Type MX
Host @
Value mx02.mail.icloud.com.
Priority 10
TXT:
Type TXT
Host @
Value apple-domain=4oc6zwBOLpmdRGr9
SPF:
Type TXT
Host @
Value "v=spf1 include:icloud.com ~all"
DKIM:
Type CNAME
Host sig1._domainkey
Value sig1.dkim.soonsoon.co.at.icloudmailadmin.com.
Here, you must ensure that your domain information is entered in the DKIM section.
After entering and clicking confirm, the process does not proceed immediately, and you are prompted to check the DNS record changes. An instruction appears stating it can take up to 72 hours, but nowadays it is usually completed within minutes.

Once completed, a success message will appear as shown below.

Now that the domain is connected, you can proceed with additional setup.
As shown below, you can see that soonsoon.co has been added to the user settings email domain at the bottom of the iCloud settings.

And as shown below, you can add the email address you want to use with that domain. In my case, I didn't add an existing email address I was using, but rather connected a new email to the soonsoon.co domain, so I added it as new.

Now you can see that the custom domain email address added below can also be used in iCloud mail settings.

Of course, now when sending emails, it is possible to select between the existing email address and the newly added email address. (Up to 3 are possible)

Additionally, it is possible to receive and manage emails arriving at different email addresses under the same iCloud email account.

It looks quite useful.
This concludes a brief overview of tips for iCloud+ users to add and use custom domains. The advantage is that you can add and use a designated domain provided by enterprise email services for a low cost of around 1,100 KRW per month. Additionally, there is the benefit of managing multiple domains and various services simultaneously from a single email account.
However, there are also downsides.. Since iCloud Mail is not really a service centered on corporate email, it feels lacking and inconvenient compared to Gmail. Naver Smartworks or Daum feel more convenient.
However, as you become more familiar with it, and if you are an iPhone or Mac user like me, the appeal of iCloud Mail is undeniable. For those who find paid business email burdensome or are already using the iCloud+ plan, this is a tip worth trying out.