[Mimedefang] Localhost Messages Cause 'reject=451 4.7.1 Please try again later'

[Jason Granat]

Help!

Watching /var/log/maillog I see everytime a message comes to 
root at mydomain.com with relay 127.0.0.1 there is an error:  'reject=451 
4.7.1 Please try again later' and MIMEDeFang times out.  What causes 
this and how do I fix it?

Thanks,

Jason