Use iCloud+ Custom Email Domain with Outlook for Windows

I think I found the solution. To re-state the issue:

Apple iCloud+ was used to create a custom domain for email.

Example: ******@customdomain.com

Apple forces you to create an @icloud address when configuring the custom domain.

Example: ******@icloud.com

Setting up apple ios and mail on the mac understand the trickery and work perfectly. You send an email, and the email comes FROM ******@customdomain.com

Outlook does NOT work so well. Emails come from ******@icloud.com. On the latest Outlook 365 (for me, it's version 2311, Build 17029), there is limited options to configure. It's trying to do everything for you. There are two built in ways to deal with this:

1. Go into the account settings, you can change the "reply to address" to be ******@customdomain.com
2. While sending an email, you can click the drop down on the FROM button and you can type in ******@customdomain.com

The result of each of the actions is the same. The emails that are received this way will show they came from ******@icloud.com <on behalf of ******@customdomain.com>. If the recipient hits reply, it will indeed go back to ******@customdomain.com, but there are numerous use cases where the FROM field is read by something automated so the Reply-To address is irrelevant.

I tried something tonight and it seems to be working to solve this. Open the registry editor, and navigate to:

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Profiles&lt;your profile name>

Press F3 and search for your icloud address (******@icloud.com)

You should see a match further down in this same branch (make sure it is). Look for a field called "Email" and the value will be your icloud address (@icloud.com). Edit this field to be your custom domain address (@customdomain.com).

Close outlook if it is open and re-open it. Emails should work normally now and the from address should be your custom domain.

Well, this appears to change the iCloud email address to the custom domain. But what if you want to keep using your apple email address and IN ADDITION use your custom domain(s)? So, the question is: how can I ADD another "inbox" that uses the custom domain?

You can't, that's the whole point of this thread. It's just that some people don't get it because they might not use the iCloud email address in the first place.

Well, first of all, that is not the entire point of this thread. The OP simply wanted to get outlook to work with his custom domain without the default method which blows.

As far as the (off topic) question of getting both of them in outlook - I can experiment a bit, but my suspicion is that if I rename the other iCloud.com address in the registry, it will reflect in outlook. Then outlook might let me add my iCloud account without complaining that it’s already there.

I must be missing something though, because if someone sends me an email to my @icloud.com address, it goes to the same inbox as my custom domain. So help me understand- why is this needed?

Well, first of all, that is not the entire point of this thread. The OP simply wanted to get outlook to work with his custom domain without the default method which blows.

As far as the (off topic) question of getting both of them in outlook - I can experiment a bit, but my suspicion is that if I rename the other iCloud.com address in the registry, it will reflect in outlook. Then outlook might let me add my iCloud account without complaining that it’s already there.

I must be missing something though, because if someone sends me an email to my @icloud.com address, it goes to the same inbox as my custom domain. So help me understand- why is this needed?

It is needed when you need to reply to emails from both the iCloud email address and the custom domain alias.