Hi all. The problem is with mail accounts of an ISP (wanadoo). When i send mail to any email address from wanadoo,orange,etc (all are the same ISP) the mails are returned with this error in my logs: server refused to talk to me: 550 Reverse DNS lookup failed for host XX.XXX. (port 25) I don't know if I have more problems, but I need to resolv this first. The IP address of my server is incomplete only the first and second octets appear. I think the mails are retuned because the other server receive an incomplete IP from my server. I try several combinations with "mynetwoks and mynetworks_style" in Postfix but nothing changes. Any idea. Thanks.