Hello, I'm running Exchange 2000 SP4. Exchange is configured to dfeliver using DNS. I have my own DNS servers internally which forward to my ISP. When I send an email to any address at "opm.gov.tt" I get a message back from "System Administrator" "permsec@opm.gov.tt on 13/01/2006 02:05 PM 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. <pai.gov.tt #5.1.1 smtp;550 5.1.1 ... User unknown>" I can send email to this user from other email services. I have tracked the message on Exchange and it reaches as far as: SMTP: Started Outbound Transfer SMTP: Non-Delivered Report (NDR) Generated I also get the following message in the System Log of the Exchange Server: " Event Source: MSExchangeTransport Event Category: Connection Manager Event ID: 4001 Message delivery to the remote domain 'opm.gov.tt' failed. The error message is 'An SMTP protocol error occurred. '. The SMTP verb which caused the error is 'RCPT'. The response from the remote server is '550 5.1.1 ... User unknown'. Data: 0000: d7 02 04 c0 ×..À " I have also succesfully Telnetted to port 25 of the destination server from my mail server. Upon entering SMTP commands I get as far as: RCPT TO: permsec@opm.gov.tt and then get a message: "550 5.1.1 permsec@opm.gov.tt... User unknown" I have also: - checked to make sure my anti-virus is not blocking the mail - checked my Message Delivery filters in Exchange I have no idea what could be the issue. Any assistance will be appreciated. -- Regards, - MPAI CITS
