530-refuse_no_reverse, ???

while trying to access an ftp-server, i am getting the following error: 530-refuse_no_reverse. could someone explain me what that means and how to figure it out?
thanx a lot
t,

Sounds like your FTP server is attempting a reverse DNS lookup on your IP address (and failing). This could be simply that its DNS server is a tad slow. How long have you been trying this site?

i am using this server for several years now, in the beginning it was working without any problems and since some months, nothing is going any more. the webmaster could not tell any useful word about the problem.