Until now I thought one IP address should have exactly one reverse dns entry... I've noticed that ISPconfig creates multiple PTR records in the pri.xxx.xxx.xxx.in-addr.arpa zone, one for each virtualhost and it's aliases. I like to use my ISPConfig-server as master dns server as well. Well, multiple ptr entries are legal but AFAIK not recommended to avoid running into trouble with spam bounce issues. Are there any experiences with this, in particular with ISPConfig?