External SMTP Authentication failing
Approximately 2 weeks ago, our network went down completely. I rebuilt our4 servers from the ground up: 1) Server 1: Domain Controller #1 (Server 2000-SP4) 2) Server 2: Domain Controller #2 (Server 2000-SP4) 3) Server 3: Web Server (Server 2000-SP4) 4)Server 4: Email Server (Server 2000-SP4/Exchange 2000-SP3) Overview of Problem: We ALLOW employees to connect to the Exchange server from their homes and the following ONLY happens when they try to access the Exchange server externally: 1) Employees CAN connect via POP3, authenticate fine and can retrieve their email. 2) Employees CAN connect VIA OWA, authenticate fine and cansend and receive email. 3) Employees CAN connect to the SMTP virtual Server to send out email from their home computer/Client BUT AUTHENTICATION FAILS and they get a '550: Unable to relay' error. SMTP Server Properties: 1) Authentication Methods allowed: Anonymous (to allow Internet delivery) and Basic Authentication (Default Domain is filled in). 2) Relay Restrictions: 'Only the list below' is set, the 'Computers' box is empty and we have the 'Allow all computers which successfully authenticate to relay, regardless of the list above'. From what I can ascertain from the server logs themselves, I see an Failure Event with Event ID of 681 telling me that the user could not be authenticated. Theerror code given is: 3221225572. Which translates to 'user unknown'. It doesn't even seem like the authentication attempt is leaving the server... It seems funny to me that they authenticate FINE for OWA and external POP3 access yet can not authenticate for the SMTP virtual server to send outgoing emails. I have verified their clients are setup properly and have the 'My server requires authentication' box checked in Outlook and Outlook Express and the appropriate parameters set under the 'Settings'.
March 30th, 2007 10:42pm

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