The Home Office are the people who deal with EU citizens requests seeking for settled status in the UK (among other things, of course), but it appears they made a bit of a mistake when sending emails to some of them asking to resubmit their information:
The Home Office sent the email on Sunday 7 April asking applicants, who had already struggled with technical problems, to resubmit their information.
But it failed to use the “blind CC” box on the email, revealing the details of other applicants.
In another message apologising to those who had been affected, the Home Office wrote: “The deletion of the email you received from us on 7 April 2019 would be greatly appreciated.” – Ross Hawkins, BBC.
Basically, someone doesn’t know the difference between CC and BCC, and now the department may have to make an apology in Parliament. Along with the fact that they breached the Data Protection Act.