Facebook's annoyed users by - all in the name of privacy and convenience - changing users' email addresses to @facebook.com versions.
It means that those users who previously elected to use their standard email address on their profile will only display the Facebook version unless they reset their controls. The @facebook.com addresses direct to a user's Messages inbox.
It means that users expecting to receive emails directly will have to check their Facebook Messages inbox - as long as they know enough to do so.
Many, though, may not even notice that the change has been made, as the company's sent out no notification as yet. The change is being implemented in stages, but will eventually be made for all the company's 900 million users.
The move follows a statement in April as part of the roll-out of Timeline. The company said then that it planned to update emailaddresses to make them more consistent over the site.
It gave no further details - and this is the result. But it's impossible not to suspect that it's simply a way of nabbing more users for itself.
The change is fixable. Users can go into their profile and select 'Update info', then 'Contact info', 'Edit' and 'Visible on Timeline' to make the original visible, rather than the Facebook version.
It's not the first time the company's made sweeping changes without informing users in advance. Our money's on a bland statement in the next few days implying that users are a bit dim for not noticing the changes all by themselves and fixing their settings without complaint.