Not existing user is using almost all his not existing disk space

Hi,



I just received a mail with the message:

"User mitchel9 has used up 0.00% of their bandwidth and 95.0% of his/her allocated disk space"



mitchel9 is a old user and doesn't exist anymore.



"# id mitchel9

id: mitchel9: No such user"



There is also no dir in "/home/mitchel9"



What to do?

Not existing user is using almost all his not existing disk space