When you set up a custom iCloud email domain you have to modify the DNS records held by your domain’s registrar. On the whole, the information provided by Apple is simple and makes it easy to set up the custom domain.
However, if you change where your domain’s name servers point, such as when you modify the hosting for a website associated with the domain, you must update the DNS records with whomever you are pointing the name servers to. Put differently: if you have configured your Apple iCloud custom email by modifying the DNS information at host X, as soon as you shift to host Y by pointing your name servers at them you will also have to update DNS records with host Y.
Now, what if you don’t do this? Eventually as DNS information propagates over the subsequent 6-72 hours you’ll be in a situation where your custom iCloud domain email address will stop sending or receiving information because the routing information is no longer valid. This will cause Apple’s iCloud custom domain system to try and re-verify the domain; it will do this because the DNS information you initially supplied is no longer valid.
Should you run into this issue you might, naturally, first reach out to Apple support. You are, after all, running your email through their servers.
Positively: you will very quickly get a real-live human on the phone to help you. That’s great! Unfortunately, however, there is very little that Apple’s support staff can do to help you. There are very, very few internal help documents pertaining to custom domains. As was explained to me, the sensitivity and complexity of DNS (and the fact that information is non-standardized across registrars) means that the support staff really can’t help much: you’re mostly on your own. This is not communicated when setting up Apple custom email domains.
In a truly worst case scenario you might get a well meaning but ignorant support member who leads you deeply astray in attempting to help troubleshoot and fix the problem. This, unfortunately, was my experience: no matter what is suggested, the solution to this problem is not solved by deleting your custom email accounts hosted by Apple on iCloud. Don’t be convinced this is ever a solution.
Worse, after deleting the email accounts associated with your custom iCloud domain email you can get into a situation where you cannot click the re-verify button on the front end of iCloud’s custom email domain interface. The result is that while you see one thing on the graphical interface—a greyed out option to ‘re-verify’—folks at Apple/server-side do not see the same status. Level 1 and 2 support staff cannot help you at this stage.
As a result, you can (at this point) be in limbo insofar as email cannot be sent or received from your custom domain. Individuals who send you message will get errors that the email identify no longer exists. The only group at Apple who can help you, in this situation, are Apple’s engineering team.
That team apparently does not work weekends.
What does this mean for using custom email domains for iCloud? For many people not a lot: they aren’t moving their hosting around and so it’s very much a ‘set and forget’ situation. However, for anyone who does have an issue the Apple support staff lacks good documentation to determine where the problem lies and, as a result, can (frankly) waste an inordinate amount of time in trying to figure out what is wrong. I would hasten to note that the final Apple support member I worked with, Derek, was amazing in identifying what the issue was, communicating the challenges facing Apple internally, and taking ownership of the problem: Derek rocks. Apple support needs more people like him.
But, in the absence of being able to hire more Dereks, Apple needs better scripts to help their support staff assist users. And, moreover, the fact that Apple lacks a large enough engineering team to also have some people working weekends to solve issues is stunning: yes, hiring is challenging and expensive, but Apple is one of the most profitable companies in the world. Their lack of a true 24/7 support staff is absurd.
What’s the solution if you ever find yourself in this situation, then? Make sure that you’ve done what you can with your new domain settings and, then, just sit back and wait while Apple tries to figure stuff out. I don’t know how, exactly, Apple fixed this problem on their end, though when it is fixed you’ll get an immediate prompt on your iOS devices that you need to update your custom domain information. It’s quick to take the information provided (which will include a new DKIM record that is unique to your new domain) and then get Apple custom iCloud email working with whomever is managing your DNS records.
Ultimately, I’m glad this was fixed for me but, simultaneously, the ability of most of Apple’s support team to provide assistance was minimal. And it meant that for 3-4 days I was entirely without my primary email address, during a busy work period. I’m very, very disappointed in how this was handled irrespective of things ultimately working once again. At a minimum, Apple needs to update its internal scripts so that their frontline staff know the right questions to ask (e.g., did you change information about your website’s DNS information?) to get stuff moving in the right direction.