Strange @domain email account

[elenlace]

Some customers have been complaining lately that a strange "nameless" account is showing up in their cpanel. This is an account without anything before the "at" sign, just an @domain account. See the attached screenshot.

The real problem is that some customers have deleted this account and then is big mess, all accounts lose their passwords and 1 customer in particular lost all his mail and we had to recicle (close/open again) the complete hosting account.

Someone from cpanel care to elaborate what is this about and how it can be fixed.

Warmest Regards