Hi guys. Now-a-days I am facing a strange problem regarding to the mail delivery. Some mails are originating from my domain with the sender as valid users to the users of other domains and receive NRDs. Users are complaining that they did not send these emails. My question is how these emails are being generated and what I need to do to stop this. In our Exchange environment we have two Exchange clusters, one front-end server, Antigen antivirus, ServerProtect antivirus and GIF anti Spam S/W. One of the NDRs is as follows: ( Our CEO did not send this email but NDR shows the CEO is sender and he received the NDR!, lot of question marks) Your message ? To:? ? ? rafiq@xxxxxxxxxx ? Subject: Answer ? Sent:? ? Tue, 21 Feb 2006 15:30:40 +0600 did not reach the following recipient(s): rafiq@xxxxxxxxxx on Wed, 22 Feb 2006 14:39:44 +0600 ? ? 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. ? ? <bestbd.com #5.1.1> Reporting-MTA: dns; ourmailserver.domain.com Final-Recipient: RFC822; rafiq@xxxxxxxxxx Action: failed Status: 5.1.1 X-Supplementary-Info: <bestbd.com #5.1.1> X-Display-Name: rafiq@xxxxxxxxxx From: "CEO" <CEO's <mailto:lpreichelt@xxxxxxxxxxxxxxxxx> email ID> Date: February 21, 2006 3:30:40 PM GMT+06:00 To: <rafiq@xxxxxxxxxx> Subject: Answer Hi! Please read quickly. Best Regards, Osman Mahmud This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. It may also be legally privileged. If you are not the named addressee, you should not copy, forward, disclose or use any part of it. If you have received this message in error, please delete it and all copies from your system and notify the sender immediately by return e-mail. Internet communications cannot be guaranteed to be timely, secure, error or virus-free. The sender does not accept liability for any errors or omissions.