Exchange2007 Que

I noticed there are several emails in our Exchange 2007 que with a email such as:
Identity: exchange2007\4335\8304
Subject: Undeliverable: Re:
Internet Message ID:
From Address: <>
Status: Active
Size (KB): 9
Message Source Name: DSN
Source IP: 255.255.255.255
SCL: -1
Date Received: 8/5/2008 11:56:34 PM
Expiration Time: 8/7/2008 11:56:34 PM
Last Error:
Queue ID: exchange2007\4335
Recipients: technicianmtb@wslco.com

I am not sure who is <>? It does not appear that we are a frame relay. Any help would be appreciated.