Why does Mail app contact iCloud when sending a non-iCloud email?

August 3 2026

I use iCloud only for testing the iCloud sync feature of my App Store apps. As I mentioned in my recent blog post Apple account email address disclosure via Mail app, I don’t have an iCloud email account. As you can see in my screenshots below, iCloud is disabled in System Settings for all uses of Mail.

Nonetheless, when I send an email in Mail app, from a non-iCloud account to an non-iCloud account, Mail immediately triggers an iCloud connection, as revealed by Little Snitch. In testing, I’ve reproduced this behavior repeatedly.

The cloudd process attempts to connect to the URL https://gateway.icloud.com:443/ckdatabase/api/client/query/retrieve , and the nsurlsessiond process attempts to connect to the URL https://gateway.icloud.com:443/ckdatabase/api/client/record/save , over both TCP and UDP, likely falling back to the alternate protocol when I block the first connection attempt.

Unfortunately, I haven’t been able to analyze the connection details with Proxyman, because iCloud uses certificate pinning, so Proxyman can’t decrypt the packets. In my testing, a network extension doesn’t get access to unencrypted data either. Thus, I don’t know the answer to the question posed by the title of this blog post: Why does Mail app contact iCloud when sending a non-iCloud email?

What could Mail be querying and saving in CloudKit when I’ve disabled Mail in iCloud? Why does Apple need to know when I’m sending emails?