Our email is on block list please help

Here is what we get:

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:

  raggedhome1@comcast.net
    host mx1.mxge.comcast.net [96.102.18.148]
    SMTP error from remote mail server after MAIL FROM:<KevinH@pls-inc.net> SIZE=603631:
    554 5.1.0 66.96.184.9 Comcast block for spam. Please see https://postmaster.comcast.net/smtp-error-codes.php#BL000000
  smjf@comcast.net
    host mx2.mxge.comcast.net [96.103.145.164]
    SMTP error from remote mail server after MAIL FROM:<KevinH@pls-inc.net> SIZE=603631:
    554 5.1.0 66.96.184.9 Comcast block for spam. Please see https://postmaster.comcast.net/smtp-error-codes.php#BL000000