Hi, mailserver cant send mails to microsoft mail server. for example: outlook.com got message: host mx1.hotmail.com[22.214.171.124] said: 550 SC-001 (COL004-MC3F20) Unfortunately, messages from 126.96.36.199 weren't sent. Please contact your Internet service provider since part of their network is on our block list. You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. (in reply to MAIL FROM command) Blacklist check @ http://mxtoolbox.com/SuperTool.aspx?action=blacklist:188.8.131.52&run=toolpage says my server is clean.