Mail sending blocked by ProofPoint

Mail sending blocked by ProofPoint

I tried to send mail this morning and got the following response:

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.

Mark_Gooch@lcca.com Invalid Address, ERROR_CODE :550, ERROR_CODE :5.7.0 Blocked - see https://support.proofpoint.com/dnsbl-lookup.cgi?ip=72.5.230.100

I clicked on the link to ProofPoint and got the following:

This IP Address is currently being blocked: 72.5.230.100

IP Lookup Information
IP Address 72.5.230.100
Reverse Lookup sender1.zohomail.com
Earliest Seen as Spam 06/28/2013 04:25:21 GMT
Most Recently Seen as Spam 08/10/2013 16:17:15 GMT
# of Spam Msgs Collected
Query Time 01/07/2014 13:46:59 GMT

Could you coordinate with them to unblock this IP or provide another way to send emails.  Thanks.