user doesn't exist on mail server
Posted on 2007-08-08
We are having a problem with a couple of sites that we send email frequently to. Some of the users at their end are getting messages back saying that the user doesn't exist at our end, yet, my users have sent and received email from the same users their end.
We are running Exchange 2003 on a Windows 2003 Small Business Server. We are also running the GFI Mail Essentials spam software on the server.
Is this a problem at our end? Is there something I can check at my end? I can send these users (at our end) email without any problems (from an external email address)