Hi guys, Could you please tell me why your servers reject emails sent from 18.104.22.168 I checked the servers mail log and found the following error 2013-01-07 21:02:14 1TsHxd-0008Lj-KQ ** firstname.lastname@example.org R=lookuphost T=remote_smtp: SMTP error from remote mail server after MAIL FROM:<email@example.com> SIZE=3832: host mx1.hotmail.com [22.214.171.124]: 550 SC-001 (COL0-MC2-F28) 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 Troubleshooting. I checked spam bases and the IP 188.8.131.52 isn't listed there. Network Tools: DNS,IP,Email Please let me know what should I do in order to get this problem fixed. Thank you. Yakiv S.