Your message cannot be delivered to the following recipients:

Recipient address: ckaplan@attglobal.net
Reason: Remote SMTP server has rejected address
Diagnostic code: smtp;551 not our customer
Remote system: dns;mx2.prserv.net (TCP|167.206.4.199|65214|12.154.55.40|25) (prserv.net - Maillennium ESMTP/MULTIBOX kcin01 #814)