Sendgrid mail being blocked.

Recently mail sent from my sendgrid account to Cox recipients is being blocked.  See the error message below.  My Sender reputation is 99%, I'm not sending spam, these are to recipients who have opted in .  All my emails contain unscubribe links.

I'm using sendgrid to send mail for membership@sandbridgecivicleague.org

What Can I do to get unblocked.

EMAIL

xxxxx@cox.net

REASON

554 cxr-ibgw-5004a.stratus.cloudmark.com cmsmtp Connection Rejected - see www.spamhaus.org/.../149.72.39.137 AUP#IPBL00001

SMTP-ID

<l0CgnTQNTH6YmUlYJIAiJw@ismtpd0007p1iad2.sendgrid.net>

PROCESSED STRING

September 15, 2020 - 07:08:59 PM

GROUP ID

14862

MSGID

l0CgnTQNTH6YmUlYJIAiJw.filterdrecv-p3las1-c5988c487-mrfnf-19-5F60ADC9-98.784