Rejected email

Can someone please help me correct this problem. I get this or a similar email almost daily. I have changed my password and I have run Kaspersky IS Virus Scan but to no avail. Thanks in advance for any assistance. 

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. The following address(es)
failed:

****@cox.net:
SMTP error from remote server for GREETING command, host: mx.west.cox.net (68.6.19.3) reason: 554 fed1rmimpi309.cox.net cox 82.165.159.130 blocked.  Error Code: IPBL000
1 - Refer to Error Codes section at http://postmaster.cox.net/confluen
ce/display/postmaster/Error+Codes for more information.