Dorsey files attachment.

[Rankin, Robert L]

For some reason I'm getting this "banned file" message for a couple of people.  I have no idea why.
 
Bob
___________________________________________________
 
Undeliverable: Banned file: Dorseyfiles.zip in mail from you
System Administrator
To: 	 Rankin, Robert L
Attachments: 	 ________________________________

Your message did not reach some or all of the intended recipients. 


Subject:	 Dorsey's Omaha and Ponca Texts.	
Sent:	 4/23/2008 4:02 PM	

The following recipient(s) could not be reached: 

  vstabler at esu1.org on 4/23/2008 4:03 PM
  You do not have permission to send to this recipient. For assistance, contact your system administrator.
  < b.nnnc.org #5.7.1 smtp; 550 5.7.1 Message content rejected, id=31426-01-252 - BANNED: Dorseyfiles.zip>