Some emails bounce back with blacklist error message

Some emails bounce back with blacklist error message

Some of my emails bounce back with the below blacklist message. I checked on  http://www.surbl.org/ where I get a message saying IP address is not blacklisted. So, I am not really sure what is going on..... 

Can somebody please help.

Thanks,

Louise

This message was created automatically by mail delivery software.

 A message that you sent could not be delivered to one or more of its recipients. This is a permanent error.

 

karincomer@worldonline.co.za INVALID_ADDRESS, ERROR_CODE :550, ERROR_CODE :rejected because 135.84.80.216 is in a black list at dnsbl-1.uceprotect.net

                                                IP 135.84.80.216 is UCEPROTECT-Level 1 listed. See

                                                http://www.uceprotect.net/rblcheck.php?ipr=135.84.80.216

 

 Received:from DESKTOP6HGE123 (196-209-228-122.dynamic.isadsl.co.za [196.209.228.122]) by mx.zohomail.com

                with SMTPS id 1508247104048628.8576144752552; Tue, 17 Oct 2017 06:31:44 -0700 (PDT)  Message-ID:<015501d3474c$4322d840$c96888c0$@greengirlsinafrica.com>

 Date:Tue, 17 Oct 2017 15:31:30 +0200

 From:"Louise de Waal" <louise@greengirlsinafrica.com>  To:"'Karin Comer'" <karincomer@worldonline.co.za>

 Subject:RE: Possible candidates for internships  Content-Type:multipart/related;

                boundary="----=_NextPart_000_0156_01D3475D.06AF78D0"