was able to email this recipient in the past and now I receive this error. He can successfully email us but a reply or test message immediately give the response below. (exchange 2003)
*****@optonline.net on 11/1/2015 7:00 PM
You do not have permission to send to this recipient. For assistance, contact your system administrator.
<HARLEQUIN.mymailserver.internal #5.7.1 smtp;550 5.7.1 Unacceptable greeting HARLEQUIN.mymailserver.internal from host my_ip_address : rejected - 01>