Hello, I have ISPConfig installed in a cluster (2 dns servers, 1 web server, 1 mail server, 1 msql server and 1 frontend) All are VPS on a oVirt cluster. I can send mails from my web server to almost all domains (included gmail) but I can't send mails to hotmail. OS: Centos 6.6 64bit ISPConfig version: 126.96.36.199.p5 Reverse dns resolve: ok spf record: "v=spf1 a include: mywebserver.com -all" For now, I have 5 domains in the mail server and yesterday one customer mailed me because cant send mails to *@hotmail.com. If *@hotmail.com send him a mail my customer and then he reply the mail the mail is delivered correctly. I checked the ssl certificate bundle in the main.cf config but nothink works. I mailed microsoft with my problem and no answer yet... I have been read the thread in ISPConfig2 forum and can't solve my problem. Anyone solved this problem before? Thanks for all!