552 5.1.1 Mailbox delivery failure policy error

552 5.1.1 Mailbox delivery failure policy error

E-mail slovenia@goslovenia.com.ua
I've deleted old emails and now I have 18% used space
But when I send messages to this box, I receive error
552 5.1.1 < slovenia@goslovenia.com.ua> Mailbox delivery failure policy error

Please, help