Sent email to Hotmail blocked


New Member
I am not able to send email from the domain to any hotmail email accounts. I always recieve error

550 SC-001 (COL004-MC6F1)
Please contact your Internet service provider since part of
their network is on our block list.


Active Member
Just putting it out there: MX ToolBox can check your domain/IP against many popular blacklists at
Unfortunately many of the more popular email hosts use their own blacklists which you have to check against using their own method, hotmail is one of them. Also Outlook, Yahoo, AOL, ATT, GMail I know have their own. Any time I find that one of my domains/IPs get blacklisted I first check mxtoolbox to see how bad the damage is. If the IP is not listed on mxtoolbox then I know the issue is usually isolated to just the one email host. Often times it's caused by someone receiving an email and marking it as junk or one of my users sent out an email to too many email addresses. mxtoolbox also has many other useful tools.


Technical Support Operator
Staff member
Having an email forwarder sending spam to Gmail / Hotmail is one of the bad ones, too.

Enabling ' Do not forward mail to external recipients if it matches the Apache SpamAssassin™ internal spam_score setting ' in WHM Home »Service Configuration »Exim Configuration Manager can help with this.


Active Member
Having an email forwarder sending spam to Gmail / Hotmail is one of the bad ones, too.
Absolutely! I once had a user forwarding their email from an account on my server to their Outlook email. Within their Outlook account they were marking many of the forwarded emails as junk, rightly so, but it was causing Outlook to identify my server as the source of the junk email. Took some time finding that issue.