-----Original Message----- From: Marvin Cummings [mailto:mcummings@xxxxxxxxxxxxxxx] Sent: Monday, October 20, 2003 10:57 AM To: [ExchangeList] Subject: [exchangelist] Relayed against or spam filter needed http://www.MSExchange.org/ I'm trying to figure out why I keep getting these emails from users and recipients who aren't apart of this network. I get something similar to the following everyday: Your message did not reach some or all of the intended recipients. Subject: RealGM Heads Up: Oct. 20th 2003 Sent: 10/20/2003 10:31 AM The following recipient(s) could not be reached: osargeant@xxxxxxxxxxxxxxx on 10/20/2003 10:37 AM The e-mail account does not exist at the organization this message was sent to. Check the e-mail address, or contact the recipient directly to find out the correct address. <dizzy.atlantalife.com #5.1.1> This user doesn't and never have been apart of this network. Is this a sign I'm being relayed against or just a need for a good spam filter? Thanks A few reasons you could get NDRs 1. someone honestly mistyped an email address so a NDR is generated 2. mistyped address subscribed to a list that doesn't verify email addresses & consent to receive their mailings 3. someone is using your domain name when posting to avoid spam 4. Spammer is trying to find valid addresses in your domain via dictionary attack 5. your domain is forged into the headers of spam so your getting the bounces and they may bounce if not to a valid user Check and see if the relay Ips are in the same netblock or listed on some of the block lists that may help to determine if this is an honest error or spam run John