My wife's email appears to be blocked

My wife’s email domain name appears to be blocked. We received notification from IONOS to say that her in box is full but we cannot access the account to delete the junk mail.

Are you sure it is IONOS that is sending that email? I say that because as an IONOS customer I get emails from spammers telling me my password is expiring or some emails are not being sent to me and I need to click on links to get it resolved, on and on and on…

As a result of logging in directly to IONOS website, using your customer ID?