[Mimedefang] Mail forged from yahoo.com

[Ravi.P CMC Engr]

Hi,

             We have configured mimedefang in our mail server. We are 
not receving some valid e-mails from yahoo.com It says

 "reject=554 5.7.1 Mail from yahoo.com not permitted from relay 
61.247.246.43"

Kindly help us to  sort out the issue

Thanking you
Ravi.P