Error: 550. Remote SMTP server has rejected address

[AdrianFURMAN.pl]

Hi,

I have a problem with my email box which was create through customer's panel. The email box acts good (example: sending a massage) but I have a problem with incoming massage. When I send email from another box to box which was created via parallel I receive this error:

Recipient address: kontakt@xxxxxx.pl
Reason: Remote SMTP server has rejected address
Diagnostic code: smtp;550 <kontakt@xxxxxxx.pl>: invalid address
Remote system: xxx;xxx.xxx.pl (TCP|xxxxxxxxxxxxxxxxxx) (mx-b.kundenserver.de [mxbap4] Welcome to Nemesis ESMTP server)

What is solution of this problem?
Thank for help