Exchange 2010: Sender address rejected: Access denied

hi friends

i have been recently experiencing an issue with one of my customer which i send email i get bounce message while i can receive their emails with no issue. i have exchange 2010 installed and im using Anti spam device too. my domain is ok.com

i try to send from OWA as well but i get the same result.

Delivery has failed to these recipients or groups:

h.orfani@abc.com A problem occurred during the delivery of this message to this e-mail address. Try sending this message again. If the problem continues, please contact your helpdesk.

Diagnostic information for administrators:

Generating server: antispamServer.ok.com

h.orfani@abc.com #< #5.0.0 X-Spam-&-Virus-Firewall; host mail.abc.com[22.22.22.12] said: 554 5.7.1 <btv1==14869c83b8f==tom.mike@ok.com: Sender address rejected: Access denied (in reply to RCPT TO command)> #SMTP#

Original message headers:

any idea?

thanks