Sinds a few days something stranges happend, cant figure it out whats wrong. Server OS: Wheezy Server Software: ISPConfig 3.0.5.4p6 server1 domain com -> (IP) 1.1.1.1; contains ispconfig3 full install, only DNS is handled extern, not by ispconfig3 Server Config -> mail -> postfix_mysql, Dovecot and sieve Real-time Blackhole List: zen(dot)spamhaus(dot)org,bl(dot)spamcop(dot)net Websites (all contains their own emails aliases like; info,webmaster,postmaster and abuse): website1(dot)com -> (IP) 2.2.2.2 website2(dot)com -> (IP) 3.3.3.3 website4(dot)com -> (IP) 4.4.4.4 website5(dot)com -> (IP) 5.5.5.5 website1(dot)com was marked as spammer atime ago. website1(dot)com was fixed and isnt on any blacklist. (all checked at www(dot)dnsstuff(dot)com) each domain contains: txt record: v=spf1 mx ptr ~all mx record points to its own domain each domain has a PTR record with its unique IP adress the problem is when i send a mail from website1(dot)com to one of these email domains: msn(dot)com, hotmail(dot)com or outlook(dot)com I get a Undelivered Mail Returned to Sender, what i dont understand is why does hotmail say that the message was send from 1.1.1.1 while it should be 2.2.2.2? I dont understand it because it was send from the website1(dot)com, is there something misconfigured. Now my server 1.1.1.1 and all other websites gets punished for something they didnt send, 2.2.2.2 is the one that send this mail? message 1) <alias@outlook(dot)com>: host mx3(dot)hotmail com[65.55.92.168] said: 550 SC-001 (SNT004-MC3F25) Unfortunately, messages from 1.1.1.1 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 mail(dot)live(dot)com/mail/troubleshooting(dot)aspx#errors. (in reply to MAIL FROM command)