A few days ago, Apple quietly announced what might have seemed like a minor change to one of its most popular privacy features - and has left some users feeling that the company is pulling the rug from underneath them.

Hide My Email is a privacy feature that lets users create unique, random email addresses that forward messages to your real inbox. That means you can sign-up for websites, newsletters, and apps without exposing your personal email address.

The benefit? Well, you can simply delete the alias if a company starts sending you unwanted email - helping to reduce your exposure to spam, marketing lists, and data brokers as well as protecting your privacy.

But now Apple has announced that it plans to move all newly-generated Hide My Email aliases from the familiar "@icloud.com" domain to "@private.icloud.com" instead.

At first sight that may seem fine. The problem is, however, that one of the reasons that Hide My Email worked so well was because its aliases were indistinguishable from regular iCloud email addresses.

When a website or app received a sign-up from an "icloud.com" address it had no way to tell if it was a genuine Apple user or someone using the privacy feature to protect themselves.

However, when Apple makes you use a "@private.icloud.com" address, the ambiguity disappears. All any website or app that wants to block anonymous sign-ups now has to do is to reject any email address ending in "@private.icloud.com".

Existing addresses on the old domains will continue to work and forward mail as before, according to Apple, but all newly-generated aliases will be issued on the new domain from later this summer.

The reaction on Reddit was predictably swift, and unsurprisingly unimpressed. Many Apple users criticised the decision, saying it would make the Hide My Email feature significantly less useful for anyone trying to sign-up anonymously for services that don't want them to.

In what was perhaps a reminder to users that Hide My Email does not guarantee anonymity, it was reported earlier this year that Apple had handed over to US law enforcement the real account details of a Hide My Email user after the account allegedly sent threatening messages to the girlfriend of FBI director Kash Patel.

For now, if you already have existing Hide My Email addresses in use, they should continue to work without any changes on your part. But if you were planning to create new aliases in the future and use them as genuinely anonymous sign-up addresses, things may be about to get more complicated.