We have a .NET application that sends emails to users inside our Exchange organization.We used to have it sending emails to the Exchange 2003 server, but now we are directing it to use or Exchange 2007 SP1 HT server.Previously, the application would send to the alias of the user, and then this would be delivered to the user's mailbox, but now we are on Exchange 2007, it refuses the connection with a 5.1.3 SMTP response.Emails to "username" are accepted by Exchange 2003, but not Exchange 2007.Emails to first.last@domain.local are accepted by all Exchange servers, and we have other applications that are able to use the HT server to send emails to internal and external recipients successfully.How can we configure Exchange 2007 to accept emails that are addressed to just the username/alias and then successfully deliver them to the internal user's mailbox?

Hi,Set default domain value on your new receive connector, this should solve your problem... :)3rd Party Application or Mail Server May Fail to Send To or Relay Mail Through Exchange Server 2007http://support.microsoft.com/kb/944302Amit Tank | MVP - Exchange | MCITP:EMA MCSA:M | http://ExchangeShare.WordPress.com

Excellent. Perfect. Just the right answer.